JP2006269866A - Magnetoresistance effect element, magnetic sensor, reproducing head, composite head, magnetic information reproducer, magnetic information recording reproducer, and magnetic information reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect magnetic information recorded at a narrower track width than the width of a magnetoresistance effect element. <P>SOLUTION: The magnetoresistance effect element 10 has a substrate 1, a lower electrode layer 2, a magnetization fixed layer 3, a nonmagnetic layer 4, an in-plane magnetized layer 7, ferrimagnetic material layer 5, and an upper electrode layer 6 laminated in this order. The ferrimagnetic material layer 5 has a high coercive force at room temperature, and the coercive force decreases at high temperatures. At reproducing magnetic information, the central part of the ferrimagnetic material layer 5 is heated to obtain a high magnetoresistance effect ratio at the central part the width of which is narrower enough than the width of the magnetoresistance element. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetoresistive effect element used for reading out magnetic recording information recorded on a magnetic recording medium such as a hard disk or a magnetic tape, a magnetic sensor including the same, a reproducing head, a composite head, a magnetic information reproducing apparatus, and a magnetic information recording. The present invention relates to a reproducing apparatus and a method for reproducing magnetic information.

  As a magnetic sensor for reproduction to read recorded magnetic recording information with high sensitivity as the magnetic recording medium represented by a hard disk increases in density, a magnetoresistive effect element in which the resistance value of the element changes due to a change in an external magnetic field A magnetoresistive sensor (MR sensor) using (MR element) is widely used.

  Among the above MR elements, the giant magnetoresistive effect element (GMR element: Giant magneto-resistive) and the tunnel magnetoresistive effect element (TMR element: Tunneling magneto-resistive) are from several percent to over 200% in some cases. Since a high magnetoresistive effect ratio (MR ratio) can be obtained, application to a magnetic sensor is actively performed as a magnetoresistive effect element suitable for a highly sensitive magnetoresistive effect sensor.

  FIG. 26 shows a schematic diagram of an example of a magnetoresistive element. This magnetoresistive effect element 200 includes a lower electrode layer 202 on a substrate 201, a magnetization fixed layer 203 whose magnetization is fixed in one direction in the plane, a nonmagnetic layer 204, and a magnetization direction within the layer formation plane by an external magnetic field. The magnetic free layer 205 and the upper electrode layer 206 are changed. The magnetoresistive effect element shown here operates by applying a voltage between the lower electrode layer 202 and the upper electrode layer 206 to generate a potential difference, and by operating a current in a direction perpendicular to the layer formation surface. This is a CPP (Current Perpendicular to Plane) type magnetoresistive element.

  The fixed magnetization layer 203 is generally formed including an antiferromagnetic layer 203a and a ferromagnetic layer 203b, and the antiferromagnetic layer 203a is unidirectional with the magnetization of the ferromagnetic layer 203b by an exchange coupling force. To increase the apparent coercive force of the ferromagnetic layer 203b. The substrate 201 is mainly a Si substrate whose surface is thermally oxidized, the lower electrode layer 202 and the upper electrode layer 206 are typically made of a metal containing Cu or Cu, and the antiferromagnetic layer 203a is typically represented by MnPt, MnFe or MnIr. As the antiferromagnetic material, Fe, CoFe, and CoFeB are mainly used for the ferromagnetic layer 203b. For the non-magnetic layer 204, Cu or a metal containing Cu is mainly used in the GMR element, and Al oxide or Mg oxide is generally used in the TMR element. As the magnetization free layer 205, Fe, CoFe, CoFeB, NiFe, or a laminate of these is used. In such a magnetoresistive effect element, the electron transmittance changes depending on the relative angle of magnetization of the magnetization fixed layer 203 (more specifically, the ferromagnetic layer 203b) and the magnetization free layer 205, and a magnetoresistance effect is generated.

  The cause of the magnetoresistive effect can be briefly described as follows. The voltage applied between the upper and lower electrode layers may be a direction in which conduction electrons move from the lower electrode layer 202 toward the upper electrode layer 206, or a direction in which the transferred electrons move from the upper electrode layer 206 toward the lower electrode layer 202. However, here, a case where a voltage is applied in a direction in which conduction electrons move from the lower electrode layer 202 toward the upper electrode layer 206 will be described.

The conduction electrons generated by applying a voltage between the upper and lower electrode layers are composed of two types of electrons having different spin angular motion directions, that is, up-spin electrons and down-spin electrons, and the same number of up-spin electrons when emitting the lower electrode layer 202. And with downspin electrons. When the conduction electrons pass through the fixed magnetization layer 203 whose magnetization is aligned in one direction, spin-dependent scattering is generated in which the amount of the passing electrons varies depending on the direction of the spin, resulting in a difference in the number of up-spin electrons and the number of down-spin electrons. . Subsequently, the conduction electrons that have passed through the nonmagnetic layer 204 cause spin-dependent scattering again when passing through the magnetization free layer 205. At this time, the magnetization direction of the magnetization fixed layer 203 and the magnetization of the magnetization free layer 205 are When the direction is substantially parallel, the amount of scattering in the magnetization free layer 205 is smaller than when the magnetization direction of the magnetization fixed layer 203 and the magnetization direction of the magnetization free layer 205 are substantially antiparallel. For this reason, the number of conduction electrons passing through the magnetization free layer 205 varies depending on the magnetization direction of the magnetization free layer 205, and the total number of conduction electrons reaching the upper electrode layer 206 changes, resulting in a change in element resistance. At this time, if the element resistance when the magnetization direction of the magnetization fixed layer 203 and the magnetization direction of the magnetization free layer 205 are substantially parallel is R _P , and the element resistance when it is approximately antiparallel is R _AP , the magnetoresistive element The MR ratio (magnetoresistance effect ratio) is defined by ΔR / R = (R _AP −R _P ) / R _P.

When such a magnetoresistive effect element is used as a reproducing magnetic sensor for reading magnetic recording information recorded on a magnetic recording medium, in addition to the above configuration, a magnetization free layer is formed at both ends of the magnetization free layer 205. A permanent magnet 210 is formed for the purpose of stabilizing (uniaxial) the magnetization of 205, and the thickness (film thickness) of the magnetization free layer 205 in the vertical direction on the paper surface determines the reproduction resolution in the track length direction and the width in the horizontal direction on the paper surface ( The width of the magnetic film determines the reproduction resolution in the track width direction. The permanent magnet 210 is mainly made of a ferromagnetic metal such as CoFePt or CoFePtCr. When the permanent magnet 210 is formed, patterning using lithography is performed, and a part of the upper layer is scraped off from the lower electrode layer 202. After that, an insulator 209 typified by SiO ₂ is formed on the side surface of the element from the magnetization fixed layer 203 to the magnetization free layer 205, and the permanent magnet 210 is disposed in direct contact with both side surfaces (see FIG. 26). ).

  When the magnetic recording medium to be read by the reproducing magnetic sensor is a perpendicular magnetic recording medium, the leakage magnetic field from this medium is applied to the magnetoresistive effect element in FIG. The paper surface becomes the medium facing surface.

  An example of the magnetoresistive element as described above is disclosed in Patent Document 1. This Patent Document 1 shows a configuration suitable for a magnetoresistive head having a magnetoresistive film, and also shows a process for forming the magnetoresistive head.

Japanese Patent Laid-Open No. 9-16918

Recently, the recording density of the magnetic recording medium is greater than 100 Gbit / inch ^2, studied with a view to practical application of 300 Gbit / inch ² is being performed. At a recording density of 300 Gbit / inch ² , the individual recording bit size is as small as 100 nm (track width direction) × 20 nm (track length direction) when the aspect ratio is 5: 1. The width of the magnetoresistive effect element of the magnetic sensor must be processed to the same or smaller size.

  Among these, the track length direction corresponds to the film thickness direction of the magnetic film constituting the magnetoresistive effect element, so that the resolution can be improved by reducing the film thickness of the magnetization free layer 205 that detects the external magnetic field. However, the track width direction is processed by a fine processing method represented by photolithography and electron beam exposure, and the resolution in the track width direction is determined by the resolution. For this reason, if the track width of the recording medium is further reduced as the density of the magnetic recording medium increases in the future, there is a problem that sufficient processing resolution cannot be obtained with the current fine processing technology.

  In addition, even if precise microfabrication can be performed by the advancement of microfabrication technology, it is difficult to realize a magnetization state having uniaxial anisotropy by a demagnetizing field by reducing the size of the magnetization free layer 205, In particular, a processed edge portion (magnetization free layer (a ferrimagnetic layer, including a high-permeability layer and an in-plane magnetization layer if formed) and a permanent magnet or an insulating region in the vicinity of the region where the permanent magnet or insulator is in contact) In the case of the side portion, there arises a problem that the magnetization easily forms a closed magnetic circuit. If the permanent magnet 210 is disposed in order to solve this problem, the magnetization is strongly fixed by the permanent magnet 210 at the edge portion of the magnetization free layer 205, so that there is a problem that the magnetization reversal at the edge portion hardly occurs. Since the influence of such an edge portion becomes more conspicuous as the element width becomes narrower (as the ratio of the edge portion becomes larger), there is a limit to a method for simply realizing an element width smaller than the track width by fine processing. It is expected that the reproducing ability of the reproducing magnetic sensor cannot be fully exhibited.

  Furthermore, in a tunnel magnetoresistive effect element (TMR element) using an insulator for the nonmagnetic material layer 204, when the element is made smaller as the track width is reduced, the junction resistance of the element increases accordingly. In addition, shot noise generated when electrons pass through the tunnel barrier becomes prominent, causing a problem of deteriorating signal quality.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a magnetoresistive effect element capable of reading magnetic recording information recorded in a track width narrower than the element width of the magnetoresistive effect element, a reproducing magnetic sensor, and a magnetic recording / reproducing using the same. To provide a head, a magnetic information recording / reproducing apparatus, and a magnetic information reproducing method.

Means and effects for solving the problems

  The magnetoresistive element of the present invention has a nonmagnetic layer and two magnetic layers sandwiching the nonmagnetic layer. A change in magnetoresistance can be obtained by a change in the relative angle of the magnetization directions of the two magnetic layers. At least one of the two magnetic layers includes a ferrimagnetic layer formed of two or more kinds of magnetic materials having antiparallel magnetization directions. Furthermore, the coercive force of the ferrimagnetic material layer changes as the temperature changes.

  According to the present invention, it is possible to obtain a magnetoresistive effect element in which the MR ratio changes according to the temperature change of the ferrimagnetic layer. That is, it is possible to detect a local external magnetic field change having a size smaller than the element size by heating or cooling a part of the ferrimagnetic layer.

Here, an example (a ferrimagnetic layer containing a rare earth metal and a transition metal) is used for the relationship between the temperature change of the magnetization amount of the ferrimagnetic layer used in the magnetoresistive element of the present invention and the temperature change of the coercive force. I will explain. FIG. 1 shows the relationship between the amount of magnetization and the change in temperature of the coercive force in a ferrimagnetic layer containing a rare earth metal and a transition metal, and the corresponding magnetization direction of the ferrimagnetic layer (layer formation surface of the ferrimagnetic layer). FIG. The compensation temperature T _comp in FIG. 1 refers to the temperature at which the coercive force becomes infinite, and the value can be adjusted by the composition ratio of the rare earth metal and the transition metal. The total magnetization M _TOT is the absolute value of the difference between the magnetization M _RE of the rare earth metal sublattice and the magnetization M _TM of the transition metal sublattice.

The principle of change in the amount of magnetization accompanying the temperature change of the ferrimagnetic material layer is shown as follows by taking an alloy of a rare earth metal and a 3d transition metal (rare earth transition metal alloy) as an example. An alloy of a heavy rare earth metal and a 3d transition metal is an amorphous metal body that exhibits ferrimagnetism in which the magnetizations of each other are antiparallel, and the difference between the magnetization of the heavy rare earth metal sublattice and the magnetization of the 3d transition metal sublattice is It is known to appear as total magnetization. Since such rare earth transition metal alloys show a decreasing tendency of magnetization in the rare earth metal sublattice and the transition metal sublattice toward the Curie temperature as the temperature rises, the total magnetization (spontaneous magnetization) varies depending on the temperature. Change. Specifically, the magnetization amount (M _RE ) of the rare earth metal sublattice is lower than the temperature at which the magnetization amount of the rare earth metal sublattice and the magnetization amount of the transition metal sublattice are the same (compensation temperature T _comp ). The total magnetization (M _TOTAL ) exceeds the amount of magnetization (M _TM ) of the lattice, and can be expressed as M _TOTAL = M _RE −M _TM . On the other hand, the magnetization of the transition metal sub-lattice in the compensation temperature (T _comp) above the temperature (M _TM) exceeds the magnetization of the rare earth metal sublattice of (M _RE), the magnetization quantity of the total (M _TOTAL) is, M _TOTAL = M _TM -M _RE Further, in the vicinity of the compensation temperature T _comp , the total magnetization amount (spontaneous magnetization amount) becomes 0, so that the external magnetic field is not sensed. For this reason, the coercive force H _c increases and theoretically increases to infinity. It is known. In the vicinity of the compensation temperature T _comp , the magnetic anisotropy energy in the direction perpendicular to the film surface is larger than the demagnetizing field energy, so that the magnetization direction is tilted from the film surface (rising from the film surface) and compensated. It is known that the temperature T _comp exhibits perpendicular magnetization.

The compensation temperature T _comp of the ferrimagnetic layer can be adjusted by the composition ratio of the rare earth metal and the transition metal. The magnetoresistive effect element of Case 1 in FIG. 1 shows an example of a ferrimagnetic material layer in which the composition ratio of the rare earth metal and the transition metal is adjusted so that the compensation temperature is higher than the room temperature _Tr . The Case 2 magnetoresistive element is an example of a ferrimagnetic layer in which the composition ratio of the rare earth metal and the transition metal is adjusted so that the compensation temperature is in the vicinity of room temperature _Tr . The Case 3 magnetoresistive effect element is an example of a ferrimagnetic layer in which the composition ratio of the rare earth metal and the transition metal is adjusted so that the compensation temperature is higher than the room temperature _Tr .

The magnetization characteristic of the ferrimagnetic material layer in the magnetoresistive effect element of Case 1 is such that the magnetization direction is ferrimagnetic as it approaches the compensation temperature T _{comp in the} temperature range T _X2 (in the region BB ′) higher than the room temperature range T _r. It gradually changes from the direction along the layer formation surface of the body layer (sometimes referred to as “in-plane direction” in this specification) to the vertical direction. In the room temperature range T _r and lower temperature range T _X1 (in the region AB), the magnetization direction remains in the in-plane direction.

As for the magnetization characteristics of the ferrimagnetic layer in the magnetoresistive effect element of Case 2, the composition ratio of the rare earth metal and the transition metal is adjusted so that the compensation temperature T _comp exists in the room temperature range T _r . in the region of 'magnetization direction will approach in a direction perpendicular to gradually plane direction toward the vicinity of the compensation temperature T _comp, it becomes perpendicular in compensation temperature T _comp. In the AB region (temperature range T _X1 lower than the room temperature range T _r ) and the B′-A ′ region (temperature range T _X2 higher than the room temperature range T _r ), which are outside the BB ′ region, the magnetization direction Is in the in-plane direction only.

The magnetization characteristics of the ferrimagnetic material layer in the Case 3 magnetoresistive effect element are such that the magnetization direction becomes in-plane as it approaches the compensation temperature T _{comp in the} temperature range T _X1 (in the region BB ′) lower than the room temperature range T _r . It gradually changes from the direction to the vertical direction. In the room temperature range T _r and higher temperature range T _X2 (in the region of B′-A ′), the magnetization direction remains in the in-plane direction.

The magnetoresistive effect element of the present invention includes all three Cases 1 to 3 shown in FIG. And the range of the effective temperature change has almost no restriction. This is because when the temperature of the magnetoresistive effect element is changed from the temperature range T _X1 to the room temperature range _Tr in Case 1 or from the temperature range T _X1 to the temperature range T _X2 , the temperature of the magnetoresistive effect element is changed in Case 2. When the temperature range T _X1 is changed to the room temperature range T _r or the temperature range T _X1 is changed to the temperature range T _X2 , the temperature of the magnetoresistive effect element is changed from the temperature range T _X2 to the room temperature range T _r in Case 3. This is because the coercive force of the ferrimagnetic material layer changes in any case such as when the temperature range T _X2 is changed to the temperature range T _X1 .

  Note that the magnetoresistive element of the present invention is such that the magnetization direction of the ferrimagnetic layer is always in the in-plane direction even if the temperature changes as long as the coercive force of the ferrimagnetic layer changes as the temperature changes. There may be.

  In another aspect, the magnetoresistive effect element of the present invention is such that the magnetization angle of the ferrimagnetic layer with respect to the layer forming surface of the ferrimagnetic layer changes as the temperature changes.

The magnetoresistive effect element of the present invention includes all three Cases 1 to 3 shown in FIG. However, the range of the effective temperature change is that the temperature in the region BB ′ where the magnetization angle of the ferrimagnetic layer is not in the in-plane direction, and the other range where the magnetization angle of the ferrimagnetic layer is in the in-plane direction. It is limited to the one that crosses the temperature (A-B or B′-A ′). For example, when the temperature of the magnetoresistive element is changed from the temperature range T _X1 or the room temperature range T _r to the temperature range T _X2 in Case 1, the temperature of the magnetoresistive element is changed from the temperature range T _X1 to the room temperature range T _r in Case 2. When the temperature is changed or when the temperature is changed from the room temperature range T _r to the temperature range T _X2 , the temperature of the magnetoresistive element is changed from the temperature range T _X1 to the room temperature range T _r or the temperature range T _X2 in Case 3. is there.

  The magnetoresistive effect element according to the present invention may obtain a magnetoresistive effect ratio larger than the magnetoresistive effect ratio at the temperature T1 at a temperature T2 higher than a certain temperature T1, or a temperature higher than room temperature. In this case, a magnetoresistive effect ratio larger than the magnetoresistive effect ratio at room temperature may be obtained. In this specification, room temperature is a temperature in the vicinity of 25 ° C.

  In the magnetoresistive effect element of the present invention, a part of the magnetoresistive effect element is heated, so that a coercive force difference is generated between a heating region and a non-heating region of the ferrimagnetic material layer. preferable.

  According to this, the coercive force of either the heated or non-heated region becomes smaller than the other coercive force, and only in the heated or non-heated region where the coercive force is small, the ferrimagnetic force reacts with the external magnetic field. Since the magnetization of the magnetic layer is reversed, a local change in the external magnetic field can be detected by converting it into a magnetoresistive effect only in a heated or non-heated region having a small coercive force.

  In the magnetoresistive element of the present invention, it is preferable that the coercive force of the ferrimagnetic layer is smaller in the heating region than in the non-heating region.

  According to this, the coercive force is reduced only in the heating region, and the ferrimagnetic layer is reversed in magnetization in response to the external magnetic field only in the heating region, so that the local external magnetic field change is converted into a magnetoresistive effect and detected. it can. In addition, since the heating region is used as the detection region, for example, when a light beam is used as a heating source, the detection resolution can be increased by reducing the light beam spot diameter.

  In the magnetoresistive element of the present invention, the layer of the ferrimagnetic layer is formed between the heated region and the non-heated region of the ferrimagnetic layer by heating a part of the magnetoresistive element. It is preferable that a difference in magnetization angle with respect to the surface occurs.

  According to this, the magnetization angle with respect to the layer forming surface of the ferrimagnetic material layer in either the heated or non-heated region is smaller than the other magnetization angle, and the layer of the ferrimagnetic material layer in the heated or non-heated region Only in the region with the smaller magnetization angle with respect to the formation surface, the magnetization of the ferrimagnetic layer is reversed in response to an external magnetic field, so the magnetization angle with respect to the layer formation surface of the ferrimagnetic layer in the heated or non-heated region is small. Only in this area, a local external magnetic field change can be converted into a magnetoresistive effect and detected.

  In the magnetoresistive element of the present invention, it is preferable that the magnetization angle with respect to the layer forming surface of the ferrimagnetic layer is smaller in the heating region than in the non-heating region.

  According to this, since the magnetization angle with respect to the layer formation surface of the ferrimagnetic material layer is smaller in the heated region than in the non-heated region, and the ferrimagnetic material layer is reversed in magnetization in response to the external magnetic field only in the region. A change in external magnetic field can be detected by converting it into a magnetoresistive effect. In addition, since the heating region is used as the detection region, for example, when a light beam is used as a heating source, the detection resolution can be increased by reducing the light beam spot.

  In the magnetoresistive effect element of the present invention, the two magnetic layers include a magnetization fixed layer, a magnetization free layer whose magnetization direction changes with a magnetic field smaller than a magnetic field when the magnetization direction of the magnetization fixed layer changes, and It may be. The magnetization free layer may include the ferrimagnetic layer.

  According to this, the coercive force of the magnetization free layer having high sensitivity to the external magnetic field can be changed by heating or cooling the ferrimagnetic material layer. Therefore, by heating or cooling the ferrimagnetic layer by heating or cooling a part of the magnetoresistive effect element, it is possible to detect a local external magnetic field change having a size smaller than the size of the magnetoresistive effect element, It is possible to increase the detection resolution for the external magnetic field.

  In the magnetoresistive element of the present invention, the ferrimagnetic material layer has at least one heavy rare earth metal element selected from Tb, Gd, Dy, Ho and at least one selected from Fe, Co, Ni. The 3d transition metal element is preferably included. According to this, a magnetoresistive effect element whose MR ratio changes with temperature can be easily realized, and a large coercive force change with respect to a temperature change, and thus a large MR ratio change with respect to a temperature change. .

  In the magnetoresistive element of the present invention, the ferrimagnetic layer includes a heavy rare earth metal element and a 3d transition metal element, the heavy rare earth metal element is Gd, and the 3d transition metal element is Co. Or Fe and Co are preferred. This makes it possible to reduce the absolute value of the coercive force when the coercive force is reduced due to temperature change, and to increase the external magnetic field sensitivity of the magnetoresistive effect element.

  In the magnetoresistance effect element of the present invention, it is preferable that the 3d transition metal element contains Fe and Co, and the composition ratio of Fe and Co is equal or the composition ratio of Co to Fe is large. According to this, a magnetoresistive effect element having a steep change in MR ratio with respect to a temperature change can be obtained. Therefore, a magnetoresistive effect element having high spatial resolution can be realized.

  Here, the manner in which the coercive force characteristic curve changes depending on the composition ratio of the metal in the material including a plurality of transition metals will be described with reference to FIG. Here, a material containing Fe and Co will be described as an example. FIG. 2 is a diagram showing how the coercive force characteristic curve changes depending on the metal composition ratio in a material containing a plurality of transition metals.

The coercive force characteristic curve according to the magnetoresistive effect element of the present invention is such that when the Fe in the material containing a plurality of transition metals is rich, the coercive force curve is represented by a dotted line in the graph of FIG. Draw. On the other hand, when Co in a material containing a plurality of transition metals is rich, a curve with a steeper slope near the compensation temperature T _comp is drawn than when Fe is rich. Accordingly, as shown in the lower part of FIG. 2, the temperature rises when the Co is rich compared to when the Fe is rich (the magnetization direction changes from the in-plane direction to the vertical direction). (Boundary width at which the magnetization rises in the graph of FIG. 2) becomes narrower. In other words, when the Co is in a rich state, the change in the magnetization direction in the vicinity of the compensation temperature T _comp becomes _sharper than when the Fe is in a rich state.

  In the magnetoresistive element of the present invention, an in-plane magnetization layer having a magnetization direction substantially parallel to the ferrimagnetic layer forming surface is formed between the ferrimagnetic layer and the nonmagnetic layer. It is preferable.

  According to this, the MR ratio of the magnetoresistive effect element can be increased. In addition, when an oxide or nitride is used for the nonmagnetic material layer, it is possible to prevent the ferrimagnetic material layer from being oxidized or nitrided and to deteriorate the characteristics, and to detect the external magnetic field in the ferrimagnetic material layer. Can also be increased.

  In the magnetoresistive effect element of the present invention, an in-plane magnetic layer having a higher magnetic permeability than the ferrimagnetic layer may be formed in contact with or magnetically coupled to the ferrimagnetic layer. preferable. According to this, the sensitivity to the external magnetic field in the ferrimagnetic material layer can be further increased.

  The magnetic sensor of the present invention includes any one of the magnetoresistive effect elements described above and an electrode for applying a current to the magnetoresistive effect element. According to this, when the temperature of the magnetoresistive effect element is raised to raise the temperature of the ferrimagnetic material, it is possible to realize a reproducing magnetic sensor that can obtain a large signal intensity only at the temperature raising portion, and the size of the magnetoresistive effect element Smaller magnetic information can be read out.

  A reproducing head according to the present invention includes a magnetic sensor including any one of the magnetoresistive elements described above, and an electrode for applying a current to the magnetoresistive element, and a heating unit for heating the magnetic sensor. The heating means raises the temperature of the ferrimagnetic layer. The magnetic information reproducing apparatus of the present invention includes this reproducing head. According to these, it is possible to provide a reproducing head and a magnetic information reproducing apparatus using the magnetoresistive effect element having the above-described effects.

  Note that the composite head of the present invention includes the reproducing head described in the paragraph immediately above and a recording head for recording magnetic information by applying a magnetic field to the magnetic recording medium. According to this, a magnetic recording / reproducing head using the magnetoresistive effect element having the above-described effect can be provided.

  In the reproducing head of the present invention, the heating means is preferably a light source. According to this, a reproducing head using the magnetoresistive effect element having the above-described effect can be provided.

  The composite head of the present invention has the reproducing head described in the paragraph immediately above and a recording head for recording magnetic information by applying a magnetic field to the magnetic recording medium, and the recording head emits near-field light. It is what was used. In the composite head, it is preferable that the light source is also used as a light source for the near-field light. According to this, it is possible to provide a magnetic recording / reproducing head suitable for light (heat) assisted recording for heating a magnetic recording medium during recording.

  The magnetic information reproducing apparatus of the present invention includes the reproducing head described above and a magnetic recording medium, and the heating means raises the temperature of the ferrimagnetic material layer. According to this, it is possible to provide a magnetic recording / reproducing apparatus capable of reading magnetic recording information with a resolution smaller than the element width of the magnetoresistive effect element.

  In the magnetic information reproducing apparatus of the present invention, a surface perpendicular to the stacking direction of the magnetoresistive elements is inclined with respect to the surface of the magnetic recording medium. According to this, when a light beam is used as the heating means, a part of the magnetoresistive element can be efficiently heated without the magnetoresistive element interfering with the optical path of the light beam.

  The magnetic information reproducing method of the present invention has a nonmagnetic layer and two magnetic layers sandwiching the nonmagnetic layer, and changes the magnetoresistance by changing the relative angle of the magnetization direction of the two magnetic layers. And a reproducing method for reproducing magnetic information recorded on a magnetic recording medium using a reproducing head in which an electrode for applying a current to the magnetoresistive element is formed. In addition, at least one of the two magnetic layers includes a ferrimagnetic layer formed of two or more kinds of magnetic bodies having magnetization directions antiparallel to each other, and the temperature is changed with the change. The coercive force of the ferrimagnetic material layer changes, and magnetic information is reproduced while the ferrimagnetic material layer is heated by heating.

  In the magnetic information reproducing method of the present invention, it is preferable to heat the ferrimagnetic material layer in advance before reproducing the recorded information recorded on the magnetic recording medium.

  According to these magnetic information reproducing methods, the magnetic recording information recorded on the magnetic recording medium can be detected with sufficient reproduction output by using the magnetoresistive effect element described above.

  One embodiment of the magnetoresistive element of the present invention will be disclosed below. FIG. 3 is a cross-sectional view showing the film configuration of the magnetoresistive element of the present invention. In the magnetoresistive effect element 10 according to this exemplary embodiment, the lower electrode layer 2, the magnetization fixed layer 3, the nonmagnetic layer 4, the in-plane magnetization layer 7, the ferrimagnetic layer 5, and the upper electrode layer 6 are sequentially formed on the substrate 1. It is formed. The magnetoresistive element 10 according to the present embodiment is a so-called CPP (Current Perpendicular to Plane) type element in which a current flows in a direction perpendicular to the layer formation surface.

  As the substrate 1, it is desirable to use a substrate having a small surface roughness. Specifically, a Si substrate, a sapphire substrate, an MgO substrate, a GaN substrate, or the like whose surface is thermally oxidized can be used.

  The lower electrode layer 2 is an electrode layer for applying a voltage from the outside of the device to flow conduction electrons into the device, and includes a material having a low electrical resistance, for example, Cu, Ag, Au, and these elements. Metal materials are suitable. In forming the lower electrode layer 2, the lower electrode layer 2 is used for the purpose of improving the adhesion between the substrate 1 and the lower electrode layer 2, or for controlling the crystal grain size, crystal structure, and surface roughness of the lower electrode layer 2. Prior to forming, a seed layer (not shown) may be formed. For this seed layer, for example, Ta, Ti, Ru, Cr, Ni, Fe, or a metal material containing these elements can be used in a single layer or in a stacked manner.

  The magnetization fixed layer 3 is composed of an antiferromagnetic layer 3a and a ferromagnetic layer 3b, and is an in-plane magnetization layer having a magnetization direction in the layer formation surface.

  The antiferromagnetic layer 3a is fabricated for the purpose of fixing the ferromagnetic layer 3b (providing unidirectional anisotropy) by exchange coupling with the ferromagnetic layer 3b formed subsequently to the antiferromagnetic layer 3a. For example, an alloy exhibiting antiferromagnetism using Mn, specifically, Mn and at least one element selected from Pt, Ir, Fe, Ru, Cr, Pd, and Ni are used in combination. be able to.

  The ferromagnetic layer 3b is given unidirectional anisotropy by exchange coupling with the antiferromagnetic layer 3a, and has an apparently higher coercive force in one direction than the case where the first ferromagnetic layer 3b is formed as a single layer. For example, it can be formed using a ferromagnetic metal such as CoFe, CoFeNi, NiFe, CoFeB, CoPt, or CoFePt.

  In forming the magnetization fixed layer 3, the purpose is to improve the adhesion between the lower electrode layer 2 and the magnetization fixed layer 3, or the crystal grains of various layers formed after the magnetization fixed layer 3 and the magnetization fixed layer 3. For the purpose of controlling the diameter, crystal structure, and surface roughness, a seed layer (not shown) may be formed prior to forming the magnetization fixed layer 3. For this seed layer, Ta, Ti, Ru, Cr, Ni, Fe, Cu, or a metal material containing these elements can be used in a single layer or in a stacked manner.

  The nonmagnetic layer 4 is made of, for example, a highly electrically conductive metal material such as Al, Cu, Au, Ag, Mg, or an alloy thereof, or an oxide or nitride thereof, The magnetic exchange coupling force with the ferrimagnetic material layer 5 is cut off, and the conduction electrons flowing in the direction perpendicular to the layer forming surface pass therethrough. Here, if the nonmagnetic layer 4 is formed using a material having a low electrical resistance, that is, a conductive metal material, the magnetoresistive element becomes a GMR element, and the material having a high electrical resistance, that is, the oxidation of the conductive metal element is performed. If a material or nitride is used, a TMR element is obtained. Further, the nonmagnetic layer 4 may be a layer in which an oxide, a nitride, or a conductive metal material is combined such that a cluster of a conductive metal material exists in the oxide or nitride. .

The ferrimagnetic layer 5 is a magnetic layer whose magnetization direction changes when receiving an external magnetic field, and a magnetic layer whose coercive force changes depending on temperature. The ferrimagnetic layer 5 is formed of a ferrimagnetic material having a compensation temperature (T _comp ) at which spontaneous magnetization is 0 and the coercive force is infinite in principle. Specifically, for example, it includes at least one heavy rare earth metal selected from Gd, Tb, Ho, and Dy and at least one 3d transition metal selected from Fe, Co, and Ni, and maintains the direction in which the layer is formed. The composition is adjusted so that the magnetic force changes at room temperature and at a temperature higher than room temperature. Accordingly, for example, if the compensation temperature (T _comp ) is set near room temperature, the coercive force is large at room temperature, and the coercive force is small at a temperature higher than room temperature. Further, the ferrimagnetic material layer 5 may be formed from an oxide ferrimagnetic material having a compensation temperature, such as ferrite, garnet-type oxide, and rare earth iron garnet. Specifically, LiFeCrO (Li—Cr ferrite), NiFeAlO (Ni—Al ferrite), YGaFeO (Ga substituted YIG), and GdFeO (Gd—Fe garnet) can be used. In addition, an element selected from B, Pt, Ru, Ta, Ti, and Cr may be added to the ferrimagnetic layer 5 mainly for the purpose of increasing the spin polarizability.

In the magnetoresistive effect element 10, the composition of the ferrimagnetic material layer 5 is adjusted so that the compensation temperature T _comp becomes room temperature. According to this, as the temperature rises or falls from room temperature, the difference between the magnetization amount (M _TM ) of the transition metal sublattice and the magnetization amount (M _RE ) of the rare earth metal sublattice increases (the temperature rises). _Along with this, M _TOTAL = M _TM −M _RE increases, and M _TOTAL = M _RE −M _TM increases as the temperature decreases. Thus, the ferrimagnetic layer 5 is obtained. That is, the ferrimagnetic material layer 5 having a very large coercive force H _c at room temperature and a small coercive force Hc as the temperature rises or falls can be realized. In other words, the magnetization angle of the ferrimagnetic material layer 5 is inclined with respect to the layer forming surface of the ferrimagnetic material layer 5 at room temperature, but in the temperature range away from room temperature as the temperature rises or falls, The ferrimagnetic material layer 5 facing the in-plane direction of the layer formation surface of the magnetic material layer 5 can be realized.

As a modification, the composition of the ferrimagnetic material layer 5 may be adjusted so that the compensation temperature T _comp is about 100 ° C. to 150 ° C. higher than room temperature. According to this, the ferrimagnetic layer 5 is obtained in which the coercive force increases with the temperature rise from room temperature and the coercive force decreases with the temperature drop from room temperature. In other words, the magnetization angle of the ferrimagnetic layer 5 is in the in-plane direction of the layer forming surface of the ferrimagnetic layer 5 at room temperature, but near the compensation temperature T _comp higher than room temperature. Thus, the ferrimagnetic material layer 5 inclined with respect to the layer forming surface 5 can be realized.

As another modification, the composition of the ferrimagnetic material layer 5 may be adjusted so that the compensation temperature T _comp is about several tens of degrees lower than room temperature. According to this, the ferrimagnetic material layer 5 is obtained in which the coercive force decreases with increasing temperature from room temperature and the coercive force increases with decreasing temperature from room temperature. In other words, the magnetization angle of the ferrimagnetic layer 5 is in the in-plane direction of the layer forming surface of the ferrimagnetic layer 5 at room temperature, but near the compensation temperature T _comp that is lower than room temperature. Thus, the ferrimagnetic material layer 5 inclined with respect to the layer forming surface 5 can be realized.

The case where an oxide ferrimagnetic material such as ferrite, garnet-type oxide, or rare earth iron garnet is used for the ferrimagnetic material layer 5 is the same as the case where the rare earth transition metal is used, and the coercive force is theoretically infinite. The vicinity of the temperature T _comp and the high temperature side and the low temperature side having a smaller coercive force are used. Even in these materials, the compensation temperature T _comp can be adjusted by changing the composition ratio.

  The ferrimagnetic layer 5 is a layer that detects an external magnetic field, and in order to increase detection sensitivity, the coercive force absolute value is small and the magnetic permeability is large at the temperature at which the magnetic field is detected (the temperature at which the coercive force becomes relatively small). It is particularly desirable to use materials that exhibit properties.

  The in-plane magnetic layer 7 has the purpose of increasing the MR ratio of the element, and that when the oxide or nitride is used for the nonmagnetic material layer 4, the ferrimagnetic material layer 5 is oxidized or nitrided and the characteristics deteriorate. It is formed between the nonmagnetic layer 4 and the ferrimagnetic layer 5 for the purpose of preventing and / or increasing the detection sensitivity of the ferrimagnetic layer 5. For the in-plane magnetic layer 7, it is desirable to use a material having a higher spin polarizability than that of the ferrimagnetic material layer, or a material that is less likely to be oxidized or nitrided than the ferrimagnetic material layer, for example, CoFe, CoFeNi, It can be formed using a material selected from NiFe, NiFeTa, NiFeNb, CoFeB, CoPt, CoFePt, and the like. The in-plane magnetization layer 7 may not be formed.

  Further, for the purpose of increasing the sensitivity to an external magnetic field, a magnetoresistive element 20 in which a high permeability layer 18 is further formed between the ferrimagnetic layer and the in-plane magnetization layer may be used (see FIG. 4: high permeability). Except for the magnetic layer 18, those having the same 1's position as in FIG. 3 have the same configuration). For the high magnetic permeability layer 28, a soft magnetic material in which an additive such as NiFe or Ta or Nb is added thereto can be used.

  Similar to the lower electrode layer 2, the upper electrode layer 6 is an electrode layer for applying a voltage from the outside of the element to flow conduction electrons into the element, and is a material having a low electrical resistance, for example, Cu, Ag , Au and metal materials containing these elements are suitable.

  In forming the upper electrode layer 6, the upper electrode layer 6 is formed for the purpose of increasing the adhesion between the ferrimagnetic material layer 5 and the upper electrode layer 6, or for controlling the crystal grain size, crystal structure, and surface roughness of the upper electrode layer 6. Prior to the formation of the electrode layer 6, a seed layer (not shown) may be formed. For this seed layer, for example, Ta, Ti, Ru, Cr, Ni, Fe, or a metal material containing these elements can be used in a single layer or in a stacked manner.

  The magnetoresistive effect element 10 according to the present exemplary embodiment generates a potential difference by applying a voltage between the lower electrode layer 2 and the upper electrode layer 6 and causes a current to flow in a direction perpendicular to the layer formation surface. It works. The conduction electrons generated by the voltage application are composed of two types of electrons having different directions of spin angular motion, that is, up-spin electrons and down-spin electrons, and have the same number of up-spin electrons and down-spin electrons. When the conduction electrons pass through the magnetization fixed layer 3 whose magnetization direction is fixed in one direction, spin-dependent scattering occurs in which the amount of passing electrons varies depending on the direction of the spin according to the magnetization direction of the magnetization fixed layer 3, and the number of up-spin electrons There is a difference in the number of downspin electrons. Subsequently, the conduction electrons that have passed through the non-magnetic layer 4 and the in-plane magnetization layer 7 cause spin-dependent scattering again when passing through the ferrimagnetic layer 5, but the magnetization direction of the magnetization fixed layer 3 and the ferrimagnetism are also reduced. When the magnetization direction of the body layer 5 is substantially parallel, the amount of scattering in the ferrimagnetic material layer 5 is smaller than when the body layer 5 is substantially antiparallel. For this reason, the number of conduction electrons passing through the ferrimagnetic material layer 5 varies depending on the magnetization direction of the ferrimagnetic material layer 5, and the total number of conduction electrons reaching the upper electrode layer 6 changes, resulting in a change in element resistance. . These magnetoresistive effects are based on the same principle as that of conventional GMR elements and TMR elements.

  Here, in the magnetoresistive effect element according to the present embodiment, since the coercive force of the ferrimagnetic layer 5 changes depending on the temperature of the element, the magnitude of the external magnetic field required to reverse the magnetization of the ferrimagnetic layer 5 is small. Varies with temperature. That is, for example, when the composition ratio of the ferrimagnetic layer 5 is set so that the coercive force of the ferrimagnetic layer 5 is large at room temperature and small at high temperature, the coercive force of the ferrimagnetic layer 5 is large at room temperature. Sensitivity to an external magnetic field (leakage magnetic field from a magnetic recording medium) is reduced, and magnetization reversal of the ferrimagnetic layer 5 hardly occurs. On the other hand, at a temperature higher than room temperature, the coercive force of the ferrimagnetic material layer 5 becomes smaller than the coercive force at room temperature, and the sensitivity to an external magnetic field is improved. Therefore, magnetization reversal can be caused by an external magnetic field smaller than room temperature. .

  As described above, the magnetoresistive effect element according to the present embodiment has low sensitivity to the external magnetic field when the coercive force of the ferrimagnetic layer 5 is large, and when the coercive force of the ferrimagnetic layer 5 is small, It has a feature that sensitivity to an external magnetic field is high, and has a feature that it can reversibly switch between a state in which the coercive force is large and a state in which the coercive force is small. Therefore, if the element temperature is locally increased by a local heating means, for example, laser light from a laser light source or a minute heater, with respect to the magnetoresistive effect element according to the present embodiment, a magnetism smaller than the element size due to the temperature distribution. A magnetoresistive sensor capable of reading recorded information can be realized.

  When using a laser light source for local heating means, by reducing the spot diameter of the laser beam to be irradiated by condensing the lens, or by using a minute near-field light generated by irradiating light to a minute aperture or minute projection, A high magnetoresistance change can be obtained with only a very small part, and a high-resolution magnetoresistive sensor can be realized.

  If such a magnetoresistive effect element is used in a reproducing magnetic sensor for reproducing information from a magnetic recording medium, it is not necessary to make the width of the magnetoresistive effect element itself smaller than the width of the information track. In addition to providing a reproducing magnetic sensor that can read magnetic recording information recorded in a narrow track width, the edge portion of the magnetization free layer that is easy to generate a closed magnetic path and is easily fixed to a permanent magnet is not used for sensing. High reproduction signal characteristics can be maintained even when reading out the minute magnetic domains.

  In addition, the magnetization layer whose coercive force changes with temperature change is the same as the magnetization free layer (in addition to the ferrimagnetic material layer, a layer including an in-plane magnetization layer and a high permeability layer). It may be used for the magnetization fixed layer.

  In the magnetoresistive effect element of the present embodiment, a so-called bottom type magnetoresistive effect element in which the magnetization fixed layer is formed first (on the substrate 1 side) than the magnetization free layer is shown. It may be a so-called top-type magnetoresistive effect element formed on the substrate 1 side and having the magnetization fixed layer formed after the nonmagnetic layer.

  Further, it may be used for a so-called double spin valve type magnetoresistive effect element in which a magnetization free layer is sandwiched between two nonmagnetic layers and the two nonmagnetic layers are further sandwiched between two magnetization fixed layers. Absent.

  The application range of the magnetoresistive effect element according to the present embodiment is not limited to a reproducing magnetic sensor for reading from a magnetic recording medium, but is represented by another magnetic sensor, MRAM (Magnetic Random Access Memory). It may be used for a magnetic memory.

  In the text, the case where the coercive force of the ferrimagnetic layer 5 is reduced at a high temperature compared to room temperature and the external magnetic field sensitivity is increased is shown. It may be a magnetoresistive element that has a small coercive force and high external magnetic field sensitivity.

Such a magnetoresistive element having a small coercive force at room temperature and a large coercive force at a high temperature higher than room temperature adjusts the composition ratio of the ferrimagnetic material layer 5 so that the total magnetization ( This can be realized by setting a compensation temperature (T _comp ) that reduces M _TOTAL ) and increases the coercive force Hc. By using the ferrimagnetic material layer 5 thus adjusted in composition, it is possible to realize a magnetoresistive effect element in which the magnetoresistive effect in the low temperature portion is larger than that in the high temperature portion. For example, laser light is emitted from a laser light source that is a local heating source. If the element temperature is locally increased by irradiation, a magnetoresistive sensor having high sensitivity only in the low temperature part can be realized without detecting a signal in the high temperature part.

  In addition to the CPP (Current Perpendicular to Plane) type magnetoresistive element that allows current to flow in a direction perpendicular to the layer forming surface, the magnetoresistive element of the present invention allows current to flow parallel to the layer forming surface. Thus, the present invention can also be applied to a CIP (Current in Plane) type magnetoresistive effect element that obtains a magnetoresistive effect. Also in this case, by using a ferrimagnetic material layer whose coercive force changes with temperature change in the magnetization free layer or the magnetization free layer and the magnetization fixed layer, magnetic recording information smaller than the element size can be obtained due to the temperature distribution. A readable magnetoresistive sensor can be realized.

Example 1
Next, examples of the magnetoresistive effect element according to the present invention are shown below. In Example 1, a sample having the same configuration as that of the magnetoresistive effect element 10 was manufactured in order to evaluate the characteristics of the magnetoresistive effect element 10 shown in FIG. A Si substrate whose surface was thermally oxidized as the substrate 1, Cu as the lower electrode layer 2 and the upper electrode layer 6, MnIr as the antiferromagnetic layer 3 a of the magnetization fixed layer 3, CoFe as the ferromagnetic layer 3 b, Al oxide obtained by oxidizing Al was formed as the magnetic layer 4, CoFe was formed as the in-plane magnetization layer 51, and GdFeCo was formed as the ferrimagnetic layer 5.

  Prior to forming the lower electrode layer 2, the lower electrode layer 2 is made of Ta for the purpose of improving the adhesion between the substrate 1 and the lower electrode layer 2 and controlling the surface roughness of the lower electrode layer 2. A seed layer (not shown) was formed.

  In the formation of the magnetization fixed layer 3, the adhesion between the lower electrode layer 2 and the magnetization fixed layer 3 is improved, and the crystal grain sizes and crystals of various layers formed after the magnetization fixed layer 3 and the magnetization fixed layer 3 are increased. In order to control the structure and the surface roughness, a seed layer (not shown) in which Ta, NiFe, and Cu are laminated is formed prior to forming the magnetization fixed layer 3.

  Prior to forming the upper electrode layer 6, the upper electrode layer 6 is formed for the purpose of improving the adhesion between the ferrimagnetic material layer 5 and the upper electrode layer 6 and controlling the surface roughness of the upper electrode layer 6. A seed layer (not shown) made of Ta was formed.

  The manufacturing method of the magnetoresistive effect element shown in this example is as follows. In addition, the film thickness shown in the following sentence is a film thickness obtained by forming a single layer film of each material on a substrate with a film thickness of about 100 nm and measuring the film thickness using a stylus step meter. And the film formation rate calculated from the film formation time. Further, for the film formation of the magnetoresistive effect element shown in this example, a magnetron sputtering apparatus provided with a film forming chamber having targets of Ta, Cu, MnIr, CoFe, NiFe, GdFeCo, and Al was used. In addition, all film-forming was performed by DC sputtering in Ar gas atmosphere.

First, a Si substrate whose surface was thermally oxidized was used as the substrate 1, and after evacuation to 1 × 10 ⁻⁶ Pa in a sputtering apparatus, Ar gas was introduced and Ta in Ta atmosphere of 1 × 10 ⁻¹ Pa was introduced. Power was supplied to the target, and Ta was deposited to a thickness of 5 nm as a seed layer (not shown) prior to the formation of the lower electrode layer 2.

  Subsequently, power was supplied to the Cu target, and Cu was deposited to a thickness of 50 nm as the lower electrode layer 2.

  Then, as a seed layer (not shown) prior to the formation of the magnetization fixed layer 3, Ta, NiFe, and Cu were stacked to a thickness of 5 nm, 2 nm, and 5 nm, respectively. Subsequently, power was supplied to the MnIr target, MnIr was formed as the antiferromagnetic layer 3a with a film thickness of 15 nm, CoFe was formed as the ferromagnetic layer 3b with a film thickness of 5 nm, and these were used as the magnetization fixed layer 3.

Next, after forming Al with a film thickness of 1.0 nm as the nonmagnetic layer 4, O ₂ gas is introduced into the chamber, and the Al is exposed to oxygen in an O ₂ atmosphere to oxidize the Al oxide film. did.

Then, CoFe was formed with a thickness of 2 nm as the in-plane magnetic layer 7 on the nonmagnetic layer 4, and subsequently, GdFeCo was formed with a thickness of 10 nm as the ferrimagnetic layer 5. The ferrimagnetic material layer 5 is a layer whose composition is adjusted so that the coercive force becomes a large compensation temperature T _comp at room temperature and the coercive force decreases as the temperature increases or decreases. Specifically, Gd was 23 at%, Fe was 23 at%, and Co was 54 at%. The ferrimagnetic material layer 5 having the above composition is a magnetic layer whose coercive force decreases monotonously and steeply as the temperature rises and has a coercive force of 100 Oe (about 8 kA / m) or less at a temperature exceeding 100 ° C. .

  Subsequently, Ta is deposited to a thickness of 5 nm as a seed layer (not shown) prior to the formation of the upper electrode layer 6, and then the Cu target is fed to form Cu with a thickness of 50 nm as the upper electrode layer 6. A film was formed.

About the element produced in the above procedure, after forming SiO ₂ with a film thickness of 100 nm on the upper electrode layer 6 as a protective film (not shown), it is 250 ° C. in a magnetic field of 500 Oe (about 40 kA / m). The magnetization fixed layer 3 was fixed by annealing in a magnetic field for a time. The magnetoresistive effect element thus manufactured was used as a sample of Example 1.

(Comparative Example 1)
For comparison with the magnetoresistive effect element of Example 1, a conventional magnetoresistive effect element was also manufactured as Comparative Example 1. Specifically, in place of the ferrimagnetic material layer 5 in Example 1, a magnetic layer using the same configuration and manufacturing method as the magnetoresistive effect element in Example 1 except that a magnetic free layer made of NiFe is formed with a film thickness of 10 nm. A resistance effect element was produced. Note that NiFe used for the free layer in Comparative Example 1 always had a small coercive force of 10 Oe (about 800 A / m) or less in the temperature range from room temperature to 250 ° C.

(Characteristic evaluation of magnetoresistive effect element of Example 1 and Comparative Example 1)
For the magnetoresistive effect element of Example 1 manufactured by the above method and the magnetoresistive effect element of Comparative Example 1 in which a magnetization free layer made of NiFe is formed in place of the ferrimagnetic layer 5, the MR ratio of each element is The results measured at temperatures of 25 ° C. and 150 ° C. are shown in FIG. 5 (results measured for the magnetoresistive effect element of Comparative Example 1) and FIG. 6 (results measured for the magnetoresistive effect element of Example 1). In the measurement, after processing the layered film using lithography and taking out the electrode, a constant voltage of 5 mV was applied between the upper and lower electrodes, and the magnetoresistive element was heated with a heater. In this state, an MR ratio was measured by applying an external magnetic field in the range of ± 1 kOe (about 80 kA / m) in the direction parallel to the layer forming surface of the magnetoresistive effect element using an electromagnet. The junction size of the element used for the measurement was 20 μm. The application direction of the external magnetic field was made parallel to the direction of the magnetic field applied when annealing in the magnetic field was performed.

  As shown in FIG. 5, in the magnetoresistive effect element of Comparative Example 1, the MR ratio of 32% at 25 ° C. (FIG. 5A) and the MR ratio of 26% at 150 ° C. (FIG. 5B). Each ratio was obtained. Although the MR ratio slightly decreased with increasing temperature, the change was small. In addition, in the magnetoresistive effect element of the comparative example, the change in the MR ratio caused by the magnetization reversal of the magnetization free layer seen in the vicinity of the zero magnetic field is 10 Oe (approximately 800 A / m) This occurred with the following external magnetic field: This reflects that NiFe used for the magnetization free layer has a low coercive force independent of temperature. Note that the change in the MR ratio seen in the vicinity of +500 Oe (about 40 kA / m) in FIG. 5 is due to the magnetization reversal of the magnetization fixed layer 3.

  On the other hand, as shown in FIG. 6, in the magnetoresistive effect element of Example 1, the coercive force of the ferrimagnetic layer 5 at 25 ° C. (FIG. 6A) is 1 kOe (about 80 kA) which is the application range of the external magnetic field. / M), the MR ratio change accompanying the magnetization reversal of the ferrimagnetic layer 5 could not be confirmed in this range. Therefore, the MR ratio in the low magnetic field in the vicinity of the zero magnetic field showed no difference between when the external magnetic field was swept in the positive direction and when the external magnetic field was swept in the negative direction. Also in this case, the change in the MR ratio seen in the vicinity of +500 Oe (about 40 kA / m) is due to the magnetization reversal of the magnetization fixed layer 3. On the other hand, in the measurement at 150 ° C. (FIG. 6B) in the magnetoresistive effect element of the present example, the coercive force of the ferrimagnetic material layer 5 decreased with increasing temperature, so that it was near zero magnetic field. Thus, the magnetization reversal of the ferrimagnetic layer 5 was observed, and a high MR ratio (33%) was confirmed in the low magnetic field region.

  As described above, the magnetoresistive effect element according to the present embodiment is characterized in that the MR ratio obtained in the low magnetic field region greatly changes due to the change in the coercive force of the ferrimagnetic layer 5 between room temperature and high temperature. Have.

  Subsequently, FIG. 7 shows the MR ratio when the magnetoresistive effect element of Example 1 is heated with a heater and heated, and measured by the same method (external magnetic field ± 1 kOe (about 80 kA / m)). Against. The MR ratio shown in FIG. 7 is the difference in MR ratio between when the external magnetic field is swept in the positive direction and when the external magnetic field is swept in the negative direction when the magnetic field is 0 Oe (0 A / m). is there. FIG. 7 also shows the results of MR ratio measured for the magnetoresistive effect element of Comparative Example 1.

  As shown in FIG. 7, in the magnetoresistive effect element of Example 1, the MR ratio, which was 0% at 25 ° C., increases as the temperature rises, and the MR ratio is 36%, which is the largest at 100 ° C. A high MR ratio of over 30% was maintained up to 200 ° C. This is because the ferrimagnetic material layer 5 having a large coercive force at 25 ° C. has a reduced coercive force as the temperature rises and has undergone magnetization reversal in accordance with an external magnetic field in a high temperature range. As a result, an MR ratio higher than the MR ratio at 25 ° C. could be obtained in the high temperature range. On the other hand, in the magnetoresistive effect element of Comparative Example 1, the MR ratio monotonously decreases with respect to the temperature as shown in FIG. 7, and the MR ratio greatly changes with the temperature change as confirmed in Example 1. I couldn't see how it did.

  FIG. 8 shows MR ratios when the range of sweeping the external magnetic field is ± 1 kOe (about 80 kA / m) and ± 100 Oe (about 8 kA / m) in the magnetoresistive effect element of Example 1. A difference between a positive sweep and a negative sweep at 0 Oe (0 A / m) will be described.

  Even when the sweep range of the external magnetic field is reduced to ± 100 Oe (about 8 kA / m), the magnetoresistive effect element of Example 1 shows a large change in the MR ratio with respect to the temperature change, and further, the sweep range is ± 1 kOe. Compared with the case of (about 80 kA / m), the change in MR ratio with respect to temperature became sharper. As described above, the magnetoresistive effect element of Example 1 has a large change amount with respect to temperature and a steep change in MR ratio even in a minute magnetic field required for use in a reproducing magnetic sensor. It is a resistance effect element.

  Further, FIG. 9 shows the result of measuring the magnetic properties (MH loop) of the ferrimagnetic layer 5 used in the magnetoresistive effect element of Example 1 using a vibrating sample magnetometer (VSM). . FIG. 9A shows an MH loop at 35 ° C. slightly higher than the compensation temperature of the ferrimagnetic material layer 5, and FIG. 9B shows an MH loop at 150 ° C. The dotted line in FIG. 9 shows the MH loop measured by applying a magnetic field parallel to the layer forming surface, and the solid line shows the MH loop measured by applying a magnetic field perpendicular to the layer forming surface. Is shown.

As shown in FIG. 9A, in the MH loop measured at 35 ° C., the MH loop (dotted line) in the direction parallel to the layer forming surface and the MH loop in the direction perpendicular to the layer forming surface. In both (solid lines), a loop with hysteresis was obtained. This is because the layer forming surface of the ferrimagnetic material layer 5 is used when the magnetization angle of the ferrimagnetic material layer 5 used in the magnetoresistive effect element of this embodiment is near the compensation temperature (T _comp ) (= 25 ° C.). It shows that it is leaning (standing up).

On the other hand, as shown in FIG. 9B, in the MH loop at 150 ° C. away from the compensation temperature (T _comp ), in the MH loop (dotted line) in the direction parallel to the layer formation surface. In addition, while a high squareness ratio was obtained and an MH loop with hysteresis was obtained, in the MH loop (solid line) in the direction perpendicular to the layer forming surface, the squareness ratio was small, and There was no hysteresis. This is because the direction of magnetization of the ferrimagnetic layer 5 used in the magnetoresistive effect element of this example is parallel to the layer formation surface at a temperature of 150 ° C. away from the compensation temperature (T _comp ). It is shown that.

  As described above, the magnetoresistive effect element according to the present embodiment may be an element in which the magnetization of the ferrimagnetic layer 5 changes in an angle with respect to the layer formation surface as the coercive force changes. If the ferrimagnetic material layer 5 showing the change in the magnetization angle in the direction inclined with respect to the layer formation surface as shown in FIG. 9 is used, the magnetization fixed layer is formed at a temperature at which the magnetization direction is parallel to the layer formation surface. Therefore, a high MR ratio is obtained and the magnetization fixed layer and the magnetization free layer are parallel / anti-parallel at temperatures where the magnetization direction is inclined perpendicularly to the layer formation surface. Since the parallel state cannot be realized, it is possible to realize a magnetoresistive element having a small MR ratio.

Further, in such a magnetoresistive element, the coercive force of the ferrimagnetic layer 5 becomes very large near the compensation temperature (T _comp ) of the ferrimagnetic layer 5 as described with reference to FIG. Thus, a state in which the magnetization reversal of the ferrimagnetic layer 5 hardly occurs is realized. At this time, even if the ferrimagnetic material layer 5 is reversed in magnetization by a large external magnetic field, as described above, if the magnetization direction is inclined perpendicular to the layer forming surface, the magnetization fixed layer and the magnetization free layer Since the parallel / antiparallel state cannot be realized, the MR ratio under the temperature can be reduced. That is, by using the characteristic that the magnetization direction is inclined with respect to the layer formation surface in combination with the characteristic that the coercive force changes with temperature, the magnetoresistance that can obtain a larger MR ratio temperature change than when only the coercive force changes in temperature. An effect element can be realized.

Note that the ferrimagnetic layer 5 included in the magnetoresistive element of this embodiment does not necessarily need to be the ferrimagnetic layer 5 whose magnetization angle changes with respect to the layer formation surface, and the magnetization direction does not depend on the temperature. It may be the ferrimagnetic layer 5 that is always parallel to the layer forming surface and only the coercive force changes in temperature. For this purpose, for example, the compensation temperature (T _comp ) can be reduced to room temperature or lower by increasing the ratio of Fe · Co, which is a 3d transition metal element, to Gd, which is a rare earth metal in the present embodiment. It is possible to realize the ferrimagnetic layer 5 in which only the above coercive force changes in temperature. As such a ferrimagnetic material, for example, Sample 3-1 in Example 3 described later corresponds.

  Further, in Example 1, the result of setting the magnetic field application range when measuring the MR ratio to be ± 1 kOe was shown, but the amount of change in coercive force accompanying the temperature change of the ferrimagnetic layer 5 does not necessarily exceed 1 kOe. There is no need. For example, when the magnetoresistive element is used in a reproducing magnetic head for reproducing magnetic recording information, the leakage magnetic field from the magnetic recording medium is about several tens Oe at most. It is sufficient that the coercive force of the layer 5 changes between a region exceeding several tens of Oe and a region below this due to temperature change.

  In the magnetoresistive effect element of Example 1, the temperature at which the MR ratio becomes maximum can be adjusted by adjusting the composition ratio of the ferrimagnetic material layer 5. Specifically, if the ratio of the rare earth metal to the 3d transition metal is higher than that of the present embodiment, the temperature at which the MR ratio becomes maximum can be increased, and conversely, if the ratio of the rare earth metal to the transition metal is decreased, the MR ratio is increased. The temperature at which becomes the largest can be lowered.

  The same applies to the temperature at which the MR ratio decreases. If the ratio of the rare earth metal to the 3d transition metal is higher than in this embodiment, the temperature at which the MR ratio decreases can be increased, and conversely the rare earth metal to the 3d transition metal. If the ratio is reduced, the temperature at which the MR ratio is reduced can be lowered.

  Furthermore, in order to adjust the difference between the temperature at which the MR ratio decreases and the temperature at which the MR ratio increases, the composition ratio in the 3d transition metal may be changed. Specifically, by increasing the ratio of Co having a high Curie temperature with respect to Fe having a low Curie temperature, the difference between the temperature at which the MR ratio decreases and the temperature at which the MR ratio increases becomes small. To obtain a sharper change. Conversely, if the ratio of Fe with a high Curie temperature is increased with respect to Co with a low Curie temperature, the temperature difference between the temperature at which the MR ratio decreases and the temperature at which the MR ratio increases increases, and it becomes more gradual with respect to the temperature. Changes can be obtained. Examples of these composition adjustments will be described in Examples 2 and 3 described later.

  Here, the film thickness of the ferrimagnetic layer of Example 1 is desirably 2 nm or more and 20 nm or less. This is because when the film thickness of the ferrimagnetic material layer is less than 2 nm, the amount of magnetization of the ferrimagnetic material layer becomes small, so that it does not react to an external magnetic field and may deteriorate the magnetic field sensitivity. Further, if the thickness of the ferrimagnetic layer exceeds 20 nm, it becomes difficult to detect a local external magnetic field change of the same size as this, and for example, the spatial resolution may be deteriorated when used for a reproducing magnetic sensor. Because there is also.

  Moreover, although Example 1 showed about the example which used GdFeCo as a ferrimagnetic material layer, it should just be a material from which a coercive force changes with a temperature change, and is not restricted to this. In particular, if a heavy rare earth alloy selected from Gd, Tb, Dy, and Ho and a 3d transition metal selected from Fe, Co, and Ni are used, a ferrimagnetic material layer exhibiting a large coercive force change with respect to temperature is formed. Can do. Furthermore, if Gd or Ho or both of these are selected as the heavy rare earth metal, the absolute value of the coercive force when the coercive force is reduced due to the temperature change can be made particularly small. A magnetoresistive effect element suitable for use as a detection element for detecting the above can be realized. In addition, as the ferrimagnetic material layer in Example 1, an oxide ferrimagnetic material made of ferrite, garnet-type oxide, or rare earth iron garnet may be used.

  In Example 1, a tunnel magnetoresistive element using an insulator as a nonmagnetic layer has been described. However, a GMR element using a conductor as a nonmagnetic layer, or a combination of an insulator and a conductor is used. The same effect can be obtained even with a current confinement type GMR element. Therefore, the present invention is not limited to the tunnel magnetoresistive element.

  In addition, a spin-valve magnetoresistive effect element that uses an antiferromagnetic layer to pin the ferromagnetic layer with an exchange coupling force has been shown for the magnetization fixed layer, but the magnetization fixed layer is not necessarily an exchange-coupled antiferromagnetic layer. And a ferromagnetic layer having a large coercive force may be used as a single layer, and a ferromagnetic film having a large coercive force and a ferromagnetic film having a small coercive force are exchange-coupled. May be used as a pinned layer, and a pinned layer (so-called synthetic structure) that has an apparently increased coercive force by sandwiching a non-magnetic material between a plurality of ferromagnetic materials and statically coupling the plurality of ferromagnetic materials. ) May be used. If the pinned layer having the synthetic structure is specifically shown, this can be realized, for example, by sequentially forming CoFe or CoFeB, Ru, CoFe or CoFeB, MnIr or MnPt from the side close to the nonmagnetic layer.

  Further, the in-plane magnetization layer may not be formed when the spin polarization of the ferrimagnetic layer is high and the MR ratio is sufficiently obtained, or when there is no fear of oxidation of the ferrimagnetic layer.

(Example 2)
Next, Example 2 according to the present invention will be described below. In this example, in the magnetoresistive effect element shown in Example 1, the composition ratio of the rare earth metal (Gd) and the 3d transition metal (Fe, Co) of GdFeCo used in the ferrimagnetic material layer 5 is constant, and Fe The composition ratio of Co and Co is changed (see Table 1 below for the composition ratio). In addition, as shown in FIGS. 9A and 9B, the samples from Sample 2-1 to Sample 2-6 shown in Table 1 are all ferrimagnetic at temperatures near the compensation temperature (T _comp ). The magnetization direction of the magnetic layer 5 indicates a magnetization direction inclined (rises) in a direction perpendicular to the layer formation surface, and the magnetization direction transitions in the in-plane direction of the layer formation surface as the distance from the compensation temperature (T _comp ) increases. It was a sample to be. The magnetoresistive effect element of this example was manufactured by the same configuration and the same manufacturing method as the magnetoresistive effect element of Example 1 except that the composition ratio of Fe and Co in the ferrimagnetic layer 15 was changed. is there. Therefore, the description of the contents already described in the first embodiment is omitted.

(Characteristic evaluation of magnetoresistive effect element in Example 2)
With respect to the magnetoresistive effect elements each having the ferrimagnetic material layer having the composition ratio shown in Table 1, the temperature at which the MR ratio becomes maximum and the value of the MR ratio at the temperature were measured. The results are also shown in Table 1. The MR ratio was measured using the same method as in Example 1, and the application range of the external magnetic field was ± 100 Oe (about 8 kA / m). Similarly to the first embodiment, the MR ratio is the MR ratio between when the external magnetic field is swept in the positive direction and when the external magnetic field is swept in the negative direction when the magnetic field is 0 Oe (0 A / m). Difference. In the example in which the composition ratio of Co and Fe in this example was changed, the compensation temperature (T _comp ) at which the coercive force was theoretically infinite in any sample was in the vicinity of room temperature (25 ° C.). . Therefore, in any element, the MR ratio at 25 ° C. (MR ratio between when the external magnetic field is swept in the positive direction and when the external magnetic field is swept in the negative direction when the magnetic field is 0 Oe (0 A / m)). Difference) was 0%.

As shown in Table 1, the temperature at which the MR ratio becomes maximum becomes lower as the ratio of Co to Fe increases, and as a result, the higher the Co ratio, the sharper the MR ratio with respect to temperature change. It has been clarified that this is an element capable of obtaining various changes. This is because the ratio of Co having a higher Curie temperature (T _c ) than that of Fe increases, the Curie temperature of the ferrimagnetic material layer 5 becomes higher, and accordingly, the compensation temperature (T _comp ) to the Curie temperature. This is because the amount of spontaneous magnetization (M _Total = M _TM −M _RE ) increases toward (T _c ). That is, since the amount of spontaneous magnetization and the coercive force are in an inversely proportional relationship, the compensation temperature (T _comp ) is a composition with a high Co ratio that exhibits a relatively large amount of spontaneous magnetization up to a temperature near the compensation temperature (T _comp ). This is probably because the low coercive force is maintained up to a temperature in the vicinity of, and the coercive force rapidly increases only in the vicinity of the compensation temperature.

In addition, as the Co ratio increases, the temperature range in which the magnetization direction of the ferrimagnetic layer 5 rises in a direction perpendicular to the layer formation surface changes at the same time as the coercive force exhibits a sharp change with respect to temperature. By increasing the Co ratio, the magnetization rises in the direction perpendicular to the layer formation surface only in the vicinity of the compensation temperature (T _comp ). Specifically, in Samples 2-5 and 2-6 with a high Co ratio, it can be observed that the magnetization rises in the vertical direction only in a very limited temperature range of 10 ° C. or less across the compensation temperature (T _comp ). There wasn't.

  On the other hand, as in Sample 2-1 and Sample 2-2 shown in Table 1, in a device having a high Fe ratio compared to Co, the device of Sample 2-3 or lower (Co is equivalent to Fe or compared to Fe). Thus, the maximum value of the MR ratio is smaller than that of a device having a high Co ratio. This is because an element having a higher ratio of Fe than Co has more Fe components having a lower Curie temperature than Co having a relatively high Curie temperature, so the Curie temperature of the ferrimagnetic layer 5 is lower and the MR ratio is lower. Since the temperature at which the temperature becomes the maximum approaches the Curie temperature, the magnetization of the ferrimagnetic layer 5 at that temperature is unstable, and the MR ratio is considered to be smaller than that of the element of sample 2-3 or lower. . In addition, it was 250 degreeC when the Curie temperature of the ferrimagnetic material layer 5 of the sample 2-1 was measured. As described above, the ferrimagnetic layer 5 is set so that the ratio of Co and Fe contained in the 3d transition metal component is approximately the same, or the ratio of Co to Fe is high, so that the MR ratio is increased with respect to the temperature. It was found that a steep change can be obtained and a higher MR ratio can be obtained.

(Example 3)
Next, Example 3 according to the present invention will be described below. In this example, in the magnetoresistive effect element shown in Example 1, the composition ratio of Fe and Co of GdFeCo used in the ferrimagnetic layer 5 is constant, and the rare earth metal (Gd) and 3d transition metal (Fe, Co) are used. ) And the composition ratio are changed (see Table 2 below for the composition ratio). The magnetoresistive effect element of this example was manufactured by the same configuration and the same manufacturing method as the magnetoresistive effect element of Example 1 except that the composition ratio of the rare earth metal and the 3d transition metal in the ferrimagnetic layer 5 was changed. It is a thing. Therefore, the description of the contents already described in the first embodiment is omitted.

(Comparison of measurement results of magnetoresistive elements in Example 3)
For magnetoresistive effect elements each having a ferrimagnetic material layer having the composition ratio shown in Table 2 above, the compensation temperature (T _comp ), the temperature at which the MR ratio is maximized, and the MR ratio at that temperature are measured. did. The results are also shown in Table 2. The MR ratio was measured using the same method as in Examples 1 and 2, and the application range of the external magnetic field was ± 100 Oe (about 8 kA / m). As for the MR ratio, as in Examples 1 and 2, the external magnetic field was swept in the positive direction and the external magnetic field was swept in the negative direction when the magnetic field was 0 Oe (0 kA / m). The difference in MR ratio was determined. The range of temperature change was between 25 ° C and 200 ° C. In this example, for samples 3-2 to 3-5, the coercive force of the ferrimagnetic layer 5 is larger than the external magnetic field (100 Oe (about 8 kA / m)) at the compensation temperature (T _comp ), and the magnetization reversal. Therefore, the MR ratio at the compensation temperature (T _comp ) (MR between the case where the external magnetic field is swept in the positive direction and the case where the external magnetic field is swept in the negative direction when the magnetic field is 0 Oe (0 kA / m)) The ratios were all 0%. Sample 3-1 had a compensation temperature (T _comp ) of 25 ° C. or lower, but the MR ratio was 0% at 25 ° C. because the coercive force of ferrimagnetic layer 5 was larger than the external magnetic field application range. It became.

As shown in Table 2, the compensation temperature (T _comp ) became higher as the ratio of rare earth metal (Gd) to 3d transition metal (Fe, Co) increased. This is because the heavy rare earth metal sublattice and the 3d transition metal sublattice are combined antiparallel to form a ferrimagnetic material. By increasing the components of the heavy rare earth metal sublattice, the heavy rare earth metal sublattice is increased. This is because the compensation temperature (T _comp ) at which the amount of magnetization and the amount of magnetization of the 3d transition metal sublattice cancel each other is shifted to the high temperature side. When the ferrimagnetic material layer 5 is formed using the rare earth transition metal composed of the heavy rare earth metal and the 3d transition metal as described above, the compensation temperature (T _comp ) can be arbitrarily set by changing the ratio of the heavy rare earth metal and the 3d transition metal. Can be set to

  Further, from Table 2, the temperature at which the MR ratio is maximum is higher than the compensation temperature in Samples 3-1 to 3-4, and these samples are heated to a temperature higher than the compensation temperature. Thus, the sample has a large MR ratio. On the other hand, Sample 3-5 had a relatively high compensation temperature of 100 ° C. or higher, so that the maximum MR ratio was obtained at 25 ° C. lower than the compensation temperature. That is, Sample 3-5 is a sample in which a large MR ratio is obtained at a low temperature near room temperature, and the MR ratio becomes extremely small when heated near the compensation temperature. Thus, in the magnetoresistive effect element of this example, by adjusting the composition ratio of the heavy rare earth metal and the 3d transition metal, either the temperature at which the MR ratio increases or the temperature at which the MR ratio becomes extremely low is higher. / It is a magnetoresistive effect element that can arbitrarily set whether to come to the low temperature side.

Of the samples shown in Table 2, in the samples shown in Sample 3-2 to Sample 3-5, the compensation temperature (T _comp ) of the ferrimagnetic material layer 5 is within the measurement temperature range (between 25 ° C. and 200 ° C. 9), in the vicinity of the compensation temperature (T _comp ), the magnetization direction of the ferrimagnetic layer 5 rises in a direction perpendicular to the layer formation surface as shown in FIG. It showed the characteristic that the magnetization direction transitioned in-plane as the distance from the temperature (T _comp ) increased. That is, these samples (sample 3-2 to sample 3-5) are in a state where the magnetization rises in a direction perpendicular to the layer formation surface at a temperature in the vicinity of the compensation temperature (T _comp ). The MR ratio can be kept particularly low in combination with the characteristic of increasing the coercive force. On the other hand, at a temperature away from the compensation temperature (T _comp ), the magnetization is parallel to the layer formation surface and the coercive force is The sample was small and could detect a small external magnetization and obtain a high MR ratio.

In Sample 3-1, the compensation temperature (T _comp ) was at a temperature lower than room temperature, and the magnetization direction of the ferrimagnetic layer 5 was always in-plane at temperatures above room temperature. That is, the characteristic of rising in the direction perpendicular to the layer formation surface was not observed. However, Sample 3-1 also shows that the MR ratio changes greatly with temperature change, and the characteristic of rising in the direction perpendicular to the layer formation surface is not essential for temperature change of MR ratio. It was confirmed that even when the inner magnetized film was used for the ferrimagnetic material layer 5, the MR ratio temperature change was obtained by changing the coercive force.

In this example, since the measurement temperature range was 25 ° C. to 200 ° C., the MR ratio was increased in samples 3-1 to 3-4 on the high temperature side and sample 3-5 on the low temperature side. Since the coercive force Hc of the rare earth transition metal having ferrimagnetism used for the ferrimagnetic material layer 5 rapidly decreases with respect to the temperature change at both the high temperature side and the low temperature side of the compensation temperature (T _comp ), the temperature of any sample is If the range is expanded, a high MR ratio can be obtained regardless of whether the compensation temperature is high or low.

Example 4
Next, Example 4 according to the present invention will be described below. In Example 4, a sample having the same configuration as that of the magnetoresistive effect element 20 was manufactured in order to evaluate the characteristics of the magnetoresistive effect element 20 shown in FIG. In the present embodiment, except for the high magnetic permeability layer 18, a layer and a seed layer (not shown) that are the same as those in the first embodiment have the same configuration and manufacturing method, and thus description of similar portions is omitted. To do.

The high magnetic permeability layer 18 was a NiFe film having a thickness of 3 nm. Also in the magnetoresistive effect element of this example, after forming SiO ₂ with a film thickness of 100 nm as a protective film (not shown) on the upper electrode layer 16 as in Example 1, 500 Oe (about 40 kA / m The magnetic pinned layer 23 was fixed by annealing in a magnetic field at 250 ° C. for 1 hour in the magnetic field of FIG. Such a magnetoresistive effect element is used as a sample of Example 4.

(Contrast of measurement results of Example 1 and Example 4)
FIG. 10 shows the results of measuring the MR ratio of the magnetoresistive effect elements of Examples 1 and 5 manufactured by the above method with respect to an external magnetic field in a state where the magnetoresistive effect element is heated to 150 ° C. with a heater. The characteristics of the magnetoresistive effect element 20 of Example 1 in which the high magnetic permeability layer is not formed are also shown. The MR ratio was measured using the same method as in Example 1, and the application range of the external magnetic field was ± 1 kOe (about 80 kA / m). FIG. 10 shows a magnetic field range of ± 100 Oe (about 8 kA / m).

  As shown in FIG. 10, the magnetoresistive effect element of this example is a magnetization free layer composed of an in-plane magnetization layer 17, a high permeability layer 18, and a ferrimagnetic layer 15 than the magnetoresistive effect element of Example 1. The coercive force of the element was small, and the element had higher magnetic field sensitivity. Specifically, the coercive force of the magnetization free layer of Example 1 (consisting of the in-plane magnetization layer 17 and the ferrimagnetic layer 15) was about 30 Oe (about 2400 A / m), whereas the magnetic force of this example was The resistance effect element was less than 10 Oe (about 800 A / m). This is because NiFe used for the high magnetic permeability layer 18 has a higher magnetic permeability and a low coercive force than GdFeCo used for the magnetization free layer 25, so that it reacts more sensitively to changes in the external magnetic field and has a high permeability. This is considered to be because the ferrimagnetic layer 15 in contact with the magnetic permeability layer 18 has undergone magnetization reversal in a lower magnetic field due to the exchange coupling force with the high magnetic permeability layer 18. Thus, the magnetoresistive effect element of this embodiment has high sensitivity to a magnetic field and can provide good characteristics as a reproducing magnetic sensor.

  The total film thickness of the ferrimagnetic material layer 15, the in-plane magnetic layer 17, and the high magnetic permeability layer 18 is desirably 20 nm or less. If the combined film thickness of the ferrimagnetic material layer 15, the in-plane magnetic layer 17, and the high magnetic permeability layer 18 exceeds 20 nm, it becomes difficult to detect a local external magnetic field change of the same size as this, for example, This is because the spatial resolution may deteriorate when used in a reproducing magnetic sensor.

  The film thickness of the single layer of the high magnetic permeability layer 18 is preferably 2 nm or more and 15 nm or less. If the thickness of the high permeability layer 18 is less than 2 nm, the sensitivity to an external magnetic field is insufficient, and the effect of reducing the coercivity of the magnetization free layer may not be obtained. If the thickness of the high permeability layer 18 is greater than 15 nm, the high permeability layer 18 cancels out the temperature change of the coercive force of the ferrimagnetic layer 15, and the change in MR ratio accompanying the temperature change is small. It is because there is a possibility of becoming.

  In the present embodiment, an example in which the high magnetic permeability layer 18 is formed between the in-plane magnetic layer 17 and the ferrimagnetic material layer 15 is shown. However, the high magnetic permeability layer 18 is exchanged with the ferrimagnetic material layer 15. What is necessary is just to be magnetically coupled by a coupling force or a magnetostatic coupling force. For example, after the in-plane magnetic layer 17 and the ferrimagnetic layer 15 are formed, the high permeability layer 18 is formed. May be. Alternatively, a nonmagnetic thin film having a thickness of about 2 nm or less may be formed between the ferrimagnetic layer 15 and the high permeability layer 18 so as to be magnetostatically coupled. Further, in the so-called top type magnetoresistive effect element in which the magnetization free layer is formed first and the magnetization fixed layer is formed later, in the reverse order to this example, that is, the ferrimagnetic material layer 15 and the high permeability layer. The magnetic layer 18 and the in-plane magnetic layer 17 may be formed in this order (not shown), or the high magnetic permeability layer 18, the ferrimagnetic layer 15, and the in-plane magnetic layer 17 may be formed in this order (not shown). .

(Example 5)
Next, Example 5 according to the present invention will be described below. In Examples 1 to 4, an example in which GdFeCo or GdCo is used as the ferrimagnetic material layer is shown, but in this example, a ferrimagnetic material layer made of another rare earth transition metal is shown (types of rare earth transition metals and (See Table 3 below for composition ratio). In addition, about the layers other than the ferrimagnetic material layer included in the magnetoresistive effect element, the configuration shown in Example 1, the same configuration as the manufacturing method, and the manufacturing method were used.

The MR ratio at 150 ° C. and the coercivity H of the ferrimagnetic layer at 150 ° C. of the magnetoresistive effect element provided with the ferrimagnetic layer having the kind and composition ratio of the rare earth transition metal shown in Table 3 above. _c was measured. The results are shown in Table 3. The MR ratio is measured by the same measurement method as that of the first embodiment. The MR ratio is measured by applying an external magnetic field in the range of ± 1 kOe (about 80 kA / m), and the magnetic field is 0 Oe (0 A / m). The difference in MR ratio between when the external magnetic field was swept in the positive direction and when the external magnetic field was swept in the negative direction was shown. In addition, in any of the materials shown in Table 3, the coercive force of the ferrimagnetic layer at 25 ° C. is 1 kOe (about 80 kA / m) or more, so that the MR ratio at 25 ° C. (magnetic field is 0 Oe ( The difference in MR ratio between the case where the external magnetic field was swept in the positive direction and the case where the external magnetic field was swept in the negative direction in the state of 0 A / m) was 0% in all samples.

  As shown in Table 3, in addition to Gd, when any heavy rare earth metal selected from Tb, Dy, and Ho is used (Samples 6-1 to 6-3), the MR ratio exceeds 20% at 150 ° C. As a result, it was revealed that it was suitable as a ferrimagnetic layer. Similarly, for GdFeCoNi (sample 6-4), an MR ratio of 32% was obtained at 150 ° C., and it was revealed that Ni may be used as the 3d transition metal element in addition to Fe and Co. On the other hand, focusing on the coercive force Hc at 180 ° C. of these samples, a coercive force of cutting 100 Oe (about 8 kA / m) can be realized when Gd and Ho are used, and Gd or Ho or It is particularly desirable to select both Gd and Ho.

  Furthermore, the MR ratio is also obtained when an element selected from B, Pt, Ru, Ta, Ti, and Cr is added to the ferrimagnetic layer composed of the heavy rare earth metal element and the 3d transition metal element shown in Table 3. When the temperature change was measured, as in Example 1 and this example, an MR ratio that did not appear at 25 ° C. appeared with temperature change, and these elements may be added. I understood.

  As described above, the material of the ferrimagnetic material layer used in the magnetoresistive effect element of the present invention is a ferrimagnetic material in which two kinds of magnetic metal elements facing in antiparallel directions are combined, and each of the materials is different with respect to temperature. Any material whose coercive force varies greatly depending on temperature can be applied by showing a decreasing tendency in which the amount of magnetization of the sublattice differs. For this purpose, it is particularly preferable to use a combination of a heavy rare earth metal element and a 3d transition metal element. Furthermore, the same effect can be obtained by adding a material selected from B, Pt, Ru, Ta, Ti, and Cr in addition to the ferrimagnetic material.

In addition, the material of the ferrimagnetic material layer of the present embodiment is not limited to the rare earth transition metal described above. Among ferrimagnetic materials, oxides having a compensation temperature, such as ferrite, garnet type oxide, and rare earth iron garnet. It may be a ferrimagnetic material. Specifically, LiFeCrO (Li—Cr ferrite), NiFeAlO (Ni—Al ferrite), YGaFeO (Ga substituted YIG), and GdFeO (Gd—Fe garnet) can be used. By using the vicinity of the compensation temperature (T _comp ) of these materials and the high temperature side or the low temperature side thereof, it can be applied as a ferrimagnetic material layer of each magnetoresistance effect element shown in Examples 1 to 5.

(Example 6)
Next, Example 6 according to the present invention will be described below. In Examples 1 to 5, an example is shown in which a ferrimagnetic material layer whose magnetization angle with respect to the layer formation surface changes depending on the temperature is used for the ferrimagnetic material layer. In this example, the ferrimagnetic material layer is fixed in magnetization. The example used for the layer is shown.

  As shown in FIG. 11, in the magnetoresistive effect element 30 of this embodiment, a lower electrode layer 22, a magnetization fixed layer 23, a nonmagnetic layer 24, a magnetization free layer 25, and an upper electrode layer 26 are sequentially formed on a substrate 21. It has been done. In this embodiment, a Si substrate whose surface is thermally oxidized is used as the substrate 21, Cu is used as the lower electrode layer 22 and the upper electrode layer 26, MnIr is used as the antiferromagnetic layer 23a in the magnetization fixed layer 23, and a ferrimagnetic material is used. TbFeCo was used as the layer 23b, Al oxide obtained by oxidizing Al as the nonmagnetic material layer 24, and CoFe and NiFe were laminated as the magnetization free layer 25, respectively.

  In forming the lower electrode layer 22, Ta is formed prior to the formation of the lower electrode layer 22 for the purpose of improving the adhesion between the substrate 21 and the lower electrode layer 22 and controlling the surface roughness of the lower electrode layer 22. A seed layer (not shown) was formed.

  In forming the magnetization fixed layer 23, the adhesion between the lower electrode layer 22 and the magnetization fixed layer 23 is improved, and the crystal grain sizes of various layers formed after the magnetization fixed layer 23 and the magnetization fixed layer 23 are increased. For the purpose of controlling the crystal structure and surface roughness, a seed layer (not shown) in which Ta, NiFe, and Cu are laminated is formed prior to forming the magnetization fixed layer 23.

  In forming the upper electrode layer 26, prior to forming the upper electrode layer 26, the adhesion between the magnetization free layer 25 and the upper electrode layer 26 is improved and the surface roughness of the upper electrode layer 26 is controlled. A Ta seed layer (not shown) was formed.

  Further, for the purpose of preventing the rare earth metal (Tb in this embodiment) used for the ferrimagnetic layer 23 b from being oxidized by oxygen contained in the oxidized Al of the nonmagnetic layer 24, the magnetization fixed layer 23 and the nonmagnetic layer 24 Between them, CoFe was formed as the in-plane magnetic layer 27.

  Here, a manufacturing method of the magnetoresistive effect element 30 shown in this embodiment will be described in detail. In addition, the film thickness shown in the following sentence is a film thickness obtained by forming a single layer film of each material on a substrate with a film thickness of about 100 nm and measuring the film thickness using a stylus step meter. And the film formation rate calculated from the film formation time. Further, for the film formation of the magnetoresistive effect element shown in this example, a magnetron sputtering apparatus provided with a film forming chamber having targets of Ta, Cu, MnIr, CoFe, NiFe, TbFeCo, and Al was used. In addition, all film-forming was performed by DC sputtering in Ar gas atmosphere. Hereinafter, the manufacturing process of the magnetoresistive effect element 30 of this embodiment will be shown in order.

First, a Si substrate whose surface was thermally oxidized was used as the substrate 21, and after evacuation to 1 × 10 ⁻⁶ Pa in a sputtering apparatus, Ar gas was introduced and Ta was introduced into an Ar atmosphere at 1 × 10 ⁻¹ Pa. Power was supplied to the target, and Ta was deposited to a thickness of 5 nm as a seed layer (not shown) prior to the formation of the lower electrode layer 32.

  Subsequently, power was supplied to the Cu target, and Cu was deposited to a thickness of 50 nm as the lower electrode layer 22. Then, as a seed layer (not shown) prior to the formation of the magnetization fixed layer 23, Ta, NiFe, and Cu were laminated to a thickness of 5 nm, 2 nm, and 5 nm, respectively.

  Subsequently, power was supplied to the MnIr target, and MnIr was formed to a thickness of 15 nm as the antiferromagnetic layer 23a, and then TbFeCo was formed to a thickness of 5 nm as the ferrimagnetic layer 23b. Here, the ferrimagnetic material layer 23b is a layer whose composition is adjusted so that the magnetization direction is inclined from the layer formation surface direction at room temperature, and the magnetization is parallel to the layer formation surface direction (in-plane magnetization layer) at 150 ° C. is there. Specifically, the ratio of Tb was 6 at%, Fe was 19 at%, and Co was 75 at%.

Then, CoFe was formed to a thickness of 2 nm as the in-plane magnetization layer 27. Subsequently, after forming Al with a thickness of 1.0 nm as the non-magnetic layer 24, O ₂ gas is introduced into the chamber, and the Al is exposed to oxygen in an O ₂ atmosphere to oxidize the Al oxide film. It was.

  Subsequently, CoFe and NiFe having a thickness of 2 nm and 15 nm were formed on the nonmagnetic layer 24 as the magnetization free layer 25, respectively. Then, Ta is formed in a film thickness of 5 nm as a seed layer (not shown) prior to the formation of the upper electrode layer 26, and Cu is formed in a film thickness of 50 nm as the upper electrode layer 26 by supplying power to the Cu target. did.

After forming SiO ₂ with a film thickness of 100 nm as a protective film on the upper electrode layer 26 of the device manufactured by the above procedure, annealing is performed in a magnetic field at 250 ° C. for 1 hour in a magnetic field of 500 Oe (about 40 kA / m). Then, the magnetization fixed layer 23 was fixed.

  FIG. 12 shows the results of measuring the MR ratio of the magnetoresistive effect element 30 of this example manufactured by the above method with respect to temperature. During measurement, a constant voltage of 5 mV was applied to the element, and an external magnetic field was applied in the range of ± 4 kOe (about 320 kA / m) in a direction parallel to the layer formation surface of the magnetoresistive element using an electromagnet. The MR ratio was measured while heating the magnetoresistive effect element 40 with a heater. The application direction of the external magnetic field was made parallel to the direction of the magnetic field applied when annealing in the magnetic field was performed.

  As shown in FIG. 12, the magnetoresistive effect element of the present example has an MR ratio that increases as the temperature rises from room temperature, the MR ratio becomes the largest at 150 ° C., and an MR ratio of 21% is obtained. It was. This is because the magnetization of the magnetization fixed layer 23 having magnetization in a direction inclined from the in-plane direction at room temperature, more specifically, the direction of magnetization of the ferrimagnetic layer 23b is parallel to the layer formation surface as the temperature rises. This is due to the change. As a result, an MR ratio higher than room temperature could be obtained at a temperature higher than room temperature.

  It is possible to adjust the temperature at which the MR ratio is maximized by adjusting the composition ratio of the ferrimagnetic layer 23b. Specifically, if the ratio of the rare earth metal to the transition metal is increased, the temperature at which the MR ratio is maximized increases. Conversely, if the ratio of the rare earth metal to the transition metal is decreased, the temperature at which the MR ratio is maximized is decreased. Can do.

  In this example, TbFeCo is used as the ferrimagnetic layer 23b. However, any material may be used as long as the magnetization direction of the layer changes between room temperature and high temperature at room temperature. is not. In particular, if a rare earth transition metal alloy is used, the ferrimagnetic layer 23b exhibiting this characteristic can be formed.

  In this embodiment, the spin valve type magnetoresistive effect element is shown in which the antiferromagnetic layer 23a is used to fix the ferrimagnetic layer 23b with exchange coupling force. However, the magnetization fixed layer 23 is not necessarily exchange coupled. The antiferromagnetic layer 23a and the ferrimagnetic material layer 23b do not need to be formed, and may be a single layer made of a ferrimagnetic material having a large coercive force. Alternatively, a ferromagnetic film having a large coercive force and a ferromagnetic film having a small coercive force may be exchange-coupled, and at least one of them may include a ferrimagnetic substance as a magnetization fixed layer, and moreover, a plurality of ferromagnetic films Using a pinned layer (so-called synthetic structure) with an apparently increased coercive force by sandwiching a non-magnetic material between the materials and magnetostatically coupling the plurality of ferromagnetic materials to a part of the plurality of ferromagnetic materials A ferrimagnetic material may be used.

  When a thermosensitive magnetic layer is used as the pinned layer as in this embodiment, the magnetization direction of the thermosensitive magnetic layer is inclined from the in-plane direction at room temperature, so the magnetization direction fixed by annealing in a magnetic field is the layer formation. There is a possibility of flipping by standing up from the surface. For this reason, when fabricating a device using a thermosensitive magnetic layer as the pinned layer, it is desirable to form a permanent magnet adjacent to the pinned layer or magnetostatically or exchange-coupled or via a nonmagnetic material. As a result, the magnetization direction of the fixed layer that becomes unstable when tilted from the layer formation surface can be fixed again.

(Example 7)
Next, Example 7 according to the present invention will be described below. In this example, a magnetoresistive effect element 20 (see FIG. 4) shown in Example 4 is processed to produce a reproducing magnetic sensor, and the reproducing characteristics are examined.

FIG. 13 shows a schematic diagram of the film configuration of the magnetoresistive effect element 40 used in the reproducing magnetic sensor manufactured in this example. In the magnetoresistive effect element 40, the magnetoresistive effect element 20 shown in the fourth embodiment is subjected to patterning by lithography, and after the magnetoresistive effect element on the lower electrode layer 32 is cut out, an insulator is formed on both sides of the magnetoresistive effect element. 39 and the permanent magnet 41 for stabilizing the magnetic characteristics are formed, and the insulator 39 and the permanent magnet 41 remaining on the upper electrode layer 36 are scraped off by a polishing process. During the patterning, the element was processed so that the element width W _E (= the width of the ferrimagnetic layer 35) was 0.4 μm. In the permanent magnet 41, an insulator 39 may be formed between the permanent magnet 41 and the ferrimagnetic layer 35, the high permeability layer 38, and the in-plane magnetization layer 37, as shown in FIG. The ferrimagnetic material layer 35, the high magnetic permeability layer 38, and the in-plane magnetic layer 37 may be in direct contact. FIG. 14 shows the positional relationship between a reproducing magnetic sensor 50 using a magnetoresistive effect element having substantially the same configuration as that of the magnetoresistive effect element 40, a heating temperature raising region 43 heated by the heating means 49, and the magnetic recording medium 44. A schematic diagram is shown.

In the reproducing magnetic sensor 50 used in this example, a magnetoresistive effect element having substantially the same configuration as the magnetoresistive effect element 40 shown in FIG. 13 is formed on a pedestal 46 made of AlTiC (Al ₂ O ₃ .TiC). In this case, a lower magnetic shield 47 and an upper magnetic shield 48 are formed above and below the magnetoresistive effect element 42 in order to suppress the influence of leakage magnetic flux from adjacent bits.

A specific manufacturing method of the reproducing magnetic sensor 50 is as follows. First, a lower magnetic shield 47 made of NiFe was formed on the gantry 46 with a thickness of 1 μm using a plating method. Subsequently, in order to prevent the lower magnetic shield 47 and the magnetoresistive effect element 40 from conducting, an insulating layer (not shown) made of Al ₂ O ₃ was formed with a film thickness of 100 nm by sputtering. Subsequently, the insulating layer is regarded as the substrate 32 of the magnetoresistive effect element 40 in FIG. 13, and after forming the magnetoresistive effect element 42 having the same configuration as the magnetoresistive effect element 40, the magnetoresistive effect element 42 and the upper magnetic field are formed. In order to prevent the shield 48 from conducting, an insulating layer (not shown) made of Al ₂ O ₃ was formed with a film thickness of 100 nm by sputtering. Subsequently, an upper magnetic shield 48 made of NiFe was formed with a film thickness of 1 μm using a plating method. With respect to the magnetoresistive effect element 42 arranged and formed in this way, the electrode 45 for supplying a sense current to the upper and lower electrodes was taken out to be used as a reproducing magnetic sensor 50. In FIG. 14, the magnetoresistive element 42 is arranged so that the paper surface in FIG. 13 faces the surface of the magnetic recording medium 44.

  In this embodiment, a GaN semiconductor laser light source 49a having a wavelength of 405 nm is used as the heating means 49 for forming the heating temperature raising region 43, and the laser beam is condensed using a lens 49b having an NA (numerical aperture) of 0.65. did. By irradiating the vicinity of the end of the reproducing magnetic sensor 50 with this, the heating temperature raising region 43 was formed. In the present embodiment, the end of the reproducing magnetic sensor 50 is irradiated with the condensed laser beam, and the region near the center in the track width direction of the reproducing magnetic sensor 50 (more specifically, the magnetoresistive effect element 42) is heated. did.

  FIG. 15 shows a magnetoresistive effect element 42 (sample 1) of this example and a conventional magnetoresistive effect element (comparative sample 1) that does not have a ferrimagnetic material layer. The output voltage when processed and used is shown with respect to the track width. Here, the magnetoresistive effect element used for the comparative sample 1 is a ferrimagnetic material after forming CoFe with a film thickness of 2 nm as an in-plane magnetization layer in the manufacturing method of the magnetoresistive effect element 42 of the present example of the sample 1. A body layer is not formed, and NiFe is formed to a thickness of 13 nm as a high permeability layer (not shown).

The magnetic recording medium 44 used for the measurement was a CoCrPtB granular type perpendicular magnetic recording medium produced on a NiP / Al substrate used as a conventional recording medium for hard disks. The aforementioned perpendicular magnetic media, had previously been multiplied by the external magnetic field using a recording magnetic head (not shown), to form a recording mark by changing the track width W _T. Track width W _T recorded on the perpendicular magnetic recording medium, a magnetic force microscope (MFM: Magnetic Force Microscope) was identified by observing with. In this example, measurement was performed by applying a sense current of 0.5 mA to the reproducing magnetic sensor 50. In the irradiation of the light beam, the irradiation power of the light beam was adjusted so that the reproduction signal output voltage was maximized. For Comparative Sample 1, the output voltage was measured while irradiating a light beam with the same irradiation power as that irradiated to Sample 1.

As shown in FIG. 15, in the comparative sample 1, an output voltage is obtained at a track width of 0.5 μm or more, but at a track width of the element width W _E (= 0.4 μm) or less, the output voltage decreases. An output voltage could not be obtained when the track width was 0.2 μm. This is because, in the comparative sample 1, when reproducing the track width W _T which is smaller than the element width W _E , the leakage magnetic field from the adjacent track is detected at the same time, so that the output voltage is lowered.

On the other hand, in Sample 1, a high output voltage was maintained even with a track width smaller than the element width W _E , and an output voltage could be obtained even with a track width of 0.2 μm. This is because, in sample 1, since the large magnetic resistance effect only near the element central portion which is heated by the laser light irradiation occurs, the leak magnetic field from the adjacent tracks even in a small track width than the element width W _E This is because it is not detected. That is, in the vicinity of the central portion of the magnetoresistive effect element of Sample 1, the coercive force of the ferrimagnetic material layer whose temperature has been increased by laser light irradiation becomes smaller than the leakage magnetic field from the magnetic recording medium 44, and leakage from the magnetic recording medium 44. Magnetization reversal is detected by detecting a magnetic field, but the region near the contact portion between the element edge portion (the magnetization free layer (ferrimagnetic layer 35, high permeability layer 38 and in-plane magnetization layer 37) in FIG. In the magnetization free layer side portion), since the temperature is lower than the center portion of the element, the coercive force of the ferrimagnetic layer 35 is larger than the leakage magnetic field from the magnetic recording medium 44, and magnetization reversal due to the leakage magnetic field does not occur. That is, the signal of the adjacent track is not read at the element edge portion. In this way, the element can detect a signal with respect to a track width smaller than the element width W _E.

  As described above, when the magnetoresistive effect element of this embodiment is used, the coercive force of the ferrimagnetic layer 35 is not less than the temperature at which the coercive force of the ferrimagnetic layer 35 is smaller than the leakage magnetic field from the magnetic recording medium 44 by the heating means, regardless of the element width. The resolution is determined by the width of the heated area. Therefore, it is possible to detect a signal with respect to the element width, that is, the track width narrower than the width of the magnetization free layer, and even if the track width becomes narrower as the medium becomes higher in density, the element width can be tracked only by microfabrication. It is not necessary to keep the width below, and the device can be easily processed. Furthermore, since the magnetization information is detected only at the central portion of the magnetoresistive effect element 42, the influence of the closed magnetic path generated at the element edge portion and the magnetization fixed to the permanent magnet 41 and difficult to reverse on the reproduction characteristics is suppressed. it can.

In this example, the result of comparing the characteristics of the magnetoresistive effect element with an element width of 0.4 μm was shown. However, even in a narrower track width, the magnetoresistive effect element of this example is theoretically more effective. it is clear that can reproduce magnetic information recorded in narrow track width than the element width W _E.

In addition, when a light beam having a wavelength of 405 nm used in this example is used and condensed and irradiated by an optical system having a numerical aperture NA of 0.65, the spot diameter (1 / e ² : e is the base of natural logarithm)) is It is about 0.5 μm, which is larger than the element width W _E used in this example. However, the magnetoresistive effect element of the present invention has a recording medium only in a portion where the temperature is increased near the center, that is, a portion where the temperature is raised to about 150 ° C. or higher in this embodiment. The leakage magnetic field from can be detected. Thus, the spot diameter of the light beam is not necessarily smaller than the element width W _E, together capable of reproducing recorded information at a resolution of under spot diameter or less, by varying the irradiation intensity of the laser beam, the reproducing resolution Can be controlled.

  In the present embodiment, the light beam arranged separately from the reproducing magnetic sensor as the element heating means is shown as an example of the heating means. However, the element heating means is not limited to this, for example, a magnetoresistive effect element. A semiconductor laser light source formed integrally with the light source may be used, and a microscopic aperture that generates near-field light or a microprojection-shaped aperture is formed integrally with the magnetic sensor for reproduction, and light emitted from the semiconductor laser light source The magnetoresistive effect element may be heated with near-field light generated by irradiating a fine opening or an opening having a fine protrusion shape. The same applies to Example 8 described later.

  A microscopic aperture or a microprojection-shaped aperture used for generating near-field light is formed with a size smaller than the light source wavelength, and a light spot diameter smaller than the light source wavelength can be realized. As a result, the recorded information on the medium can be reproduced with extremely high resolution. Specifically, for example, a fine opening of 100 nm or less (see FIGS. 16A and 16B) formed in a metal plate by etching using FIB (Focused Ion Beam) or an opening having a fine protrusion shape (see FIG. 16 (c), (d)) can be formed on the reproducing magnetic sensor 50. If a parallel laser beam is irradiated here in the depth direction of the paper, a spot diameter of 100 nm or less can be realized, and a heating temperature raising region 43 of the same size or less can be formed. It becomes a heating means suitable for a magnetic sensor. Furthermore, a heat source other than light, such as a heater, may be used as the element local heat source. The same applies to Example 8 described later. In FIGS. 16A to 16D, the hatched portion in each figure represents a metal mask, and the portion without the hatched line is nothing or is a transparent substrate (for example, quartz or glass).

  Further, the heating method of the magnetoresistive effect element 42 is such that the central portion of the magnetoresistive effect element 42 is secondarily heated by the radiant heat generated by the heating means heating the magnetic recording medium 44 as in this embodiment. Alternatively, the heating means may be a method of directly heating the magnetoresistive effect element 42, or both of them may be used. The same applies to Example 8 described later.

  The reproducing magnetic sensor 50 shown in this embodiment may be integrated with this to form a recording magnetic head. The same applies to Example 8 described later.

  In the present embodiment, the end of the reproducing magnetic sensor 50 is irradiated with the focused laser beam, and the region near the center of the magnetoresistive effect element 42 (near the center in the track width direction) is heated. Also, the focused laser beam is irradiated onto the magnetic recording medium 44 near the end of the reproducing magnetic sensor 50, the magnetic recording medium 44 is heated, and the region near the center of the magnetoresistive effect element 42 is heated by the radiant heat. It doesn't matter. At this time, the magnetic recording medium 44 is moving in the medium moving direction shown in FIG. 14, and the heating temperature raising region 43 passes under the reproducing magnetic sensor 50 immediately after being heated by the heating means. Thus, the radiant heat can efficiently locally heat the central portion of the reproducing magnetic sensor 50 (more specifically, the magnetoresistive effect element 42). The same applies to Example 8 described later.

  Further, on the facing surface of the reproducing magnetic sensor 50 shown in the present embodiment facing the magnetic recording medium 44, the purpose of preventing wear due to rubbing with the magnetic recording medium 44 and the characteristics of the magnetoresistive effect element 42 are oxidized. A protective film may be formed for the purpose of preventing deterioration. The same applies to Example 8 described later.

(Example 8)
Next, Example 8 according to the present invention will be described below. In this example, instead of the CoCrPtB granular medium used for the magnetic recording medium 54 in Example 7, Al was 5 nm, TbFeCo was 50 nm, AlN was 2 nm, and DLC (diamond-like carbon) on a 1.2 mm thick glass substrate. The signal output with respect to the track width W _T was examined using rare earth transition metal perpendicular magnetic recording media each having a thickness of 2 nm. The members and measurement methods identical to those in Example 7 were used except for the magnetic recording medium 44.

The magnetic recording medium used in this example is set so that the composition of TbFeCo is in the vicinity of the compensation temperature (T _comp ) at room temperature, and almost no leakage magnetic field is generated at room temperature, but is higher than room temperature and below the Curie temperature. It is a magnetic recording medium that generates a leakage magnetic field at a temperature of. Since the magnetic recording medium has a large coercive force at room temperature and cannot be recorded only by a recording magnetic head, the medium is heated in advance to a temperature above the Curie temperature by irradiation with a laser beam, and a recording magnetic head (not shown) multiplied by the external magnetic field with and allowed to form a recording mark by changing the track width W _T. Track width W _T recorded on the perpendicular magnetic recording medium, a magnetic force microscope (MFM: Magnetic Force Microscope) was identified by observing with. FIG. 17 shows the result of the output voltage with respect to the track width of the magnetic recording information recorded on the magnetic recording medium, measured by the same method as in Example 7, together with the result of the output voltage of Example 7.

  As shown in FIG. 17, in this embodiment, it is understood that a signal output is obtained up to a narrower track width than in the seventh embodiment, and the reproduction resolution in the track width direction is further increased. This is because, in the same way as in the seventh embodiment, the central portion of the magnetoresistive effect element 42 of the present invention is heated and the resolution in the track width direction of the reproducing magnetic sensor 50 is increased. Since the magnetic recording medium hardly generates a leakage magnetic field at room temperature and generates a leakage magnetic field only at a high temperature, only the magnetization in the vicinity of the track center where the heating temperature raising region 43 is formed by the heating means generates the leakage magnetic field. This is because the leakage magnetic field from the adjacent track is more difficult to detect. As described above, the magnetoresistive effect element 42 and the reproducing magnetic sensor 50 are magnetic recording media in which the magnitude of the leakage magnetic field changes depending on the temperature, specifically, for example, a magnet using a rare earth transition metal alloy. It is more desirable to use with a recording medium. When used together with a magnetic recording medium in which the magnitude of the leakage magnetic field changes depending on the temperature, magnetic recording information can be reproduced with higher resolution.

  In addition, regarding a reproducing magnetic sensor having substantially the same configuration as the reproducing magnetic sensor 50 used in Examples 7 and 8, a more preferable arrangement when a laser light source is used as a heating source will be disclosed below. In the seventh and eighth embodiments, as shown in FIG. 14, the example in which the stacking direction of the magnetoresistive effect element 42 is arranged perpendicular to the facing surface of the magnetic recording medium 54 is shown. 18 shows an example of a reproducing magnetic sensor 60 in which the magnetoresistive effect element 52 is disposed obliquely with respect to the facing surface of the magnetic recording medium 54.

  As shown in FIG. 14, in the system in which the layer forming surface of the magnetoresistive element 52 is arranged perpendicular to the opposing surface of the magnetic recording medium 54, a light beam emitted from a laser light source is very close to the reproducing magnetic sensor 60. When the heating temperature raising region 53 is formed, the reproducing magnetic sensor 60 easily interferes with a part of the light beam path, and it is difficult to irradiate without reducing the amount of light in the heating temperature raising region 53. . Such interference of the reproducing magnetic sensor 60 with the light beam path is likely to occur particularly in a system for condensing the light beam with a lens, and the light is condensed using an optical system having a higher numerical aperture (NA) (light It becomes more noticeable as the beam is narrowed down.

  Therefore, if the surface perpendicular to the stacking direction of the magnetoresistive element 52 is inclined with respect to the surface of the magnetic recording medium 54 as shown in FIG. 18, the reproducing magnetic sensor 60 does not interfere with the path of the light beam, and the magnetic recording is performed. Even if the light beam is irradiated from directly above the medium 54, it is possible to prevent a decrease in the amount of light in the heating temperature raising region 53.

  Furthermore, as compared with the case where the layer forming surface of the magnetoresistive effect element 42 is arranged perpendicular to the opposing surface of the magnetic recording medium 44 as shown in FIG. The thickness can be reduced. That is, the heating efficiency of the reproducing magnetic sensor 60 when the light beam is irradiated can be increased.

  The resolution of the magnetoresistive effect element of the present invention is determined by the size of the region heated to a certain temperature or higher by the heating means, regardless of the element width. Therefore, the magnetoresistive effect element is as shown in FIGS. The element width direction of the magnetoresistive effect element in the track length direction of the magnetic recording medium and the film thickness direction of the magnetoresistive effect element in the track width direction in a state of being arranged perpendicularly and obliquely to the facing surface of the magnetic recording medium It is also possible to arrange and use the reproducing magnetic sensors 50 and 60 in correspondence with each other (in the direction rotated 90 degrees on the medium facing surface).

Example 9
Next, Example 9 according to the present invention will be described below. FIG. 19 shows a magnetic recording / reproducing head of this example. The magnetic recording / reproducing head 71 shown in FIG. 19 has an AlTiC (Al ₂ O ₃₎ in which an air bearing surface 72 for floating the magnetic recording / reproducing head 71 by an air flow generated when the magnetic recording medium rotates is processed. A lower magnetic shield 74, an optical waveguide 75, a magnetoresistive effect element 70, an insulating layer 76, and an upper magnetic shield 77 are formed in this order on a head substrate 73 made of TiC), and further, information is recorded on a magnetic recording medium. For this purpose, a thin film coil 78 and a magnetic pole 79 are formed. A transparent dielectric film 80 and a surface emitting laser light source 81 are formed on the magnetic recording / reproducing head 71 in contact with the optical waveguide 75. The magnetoresistive effect element 70 is any one of the magnetoresistive effect elements shown in the above embodiment and examples.

  In the magnetic recording / reproducing head of this embodiment, in order to perform perpendicular magnetic recording on the magnetic recording medium, the upper magnetic shield 77 also serves as a return magnetic pole from which the magnetic field emitted from the magnetic pole 79 returns from the magnetic recording medium. As the surface emitting laser light source 81, for example, a GaN surface emitting laser light source that emits laser light having a wavelength of around 405 nm is used.

The magnetic recording / reproducing head 71 of this embodiment is formed by the following procedure. First, a lower magnetic shield 74 made of NiFe is formed with a film thickness of 1 μm to 3 μm on a head base 73 made of AlTiC (Al ₂ O ₃ .TiC) by sputtering or plating.

Subsequently, a transparent high refractive index material is formed as the optical waveguide 75 with a film thickness of about 100 nm to 400 nm by sputtering. As the transparent highly refractive material, for example, a material selected from ZnO, ZnS, TiO ₂ , PbTiO ₂ , Pb ₃ O ₄ , PbCrO ₄ , Cr ₂ O ₃ , and ZrO can be selected. The film thickness d of the optical waveguide 75 is preferably calculated from the wavelength λ of the surface emitting laser light source 81 used as the light source and the refractive index n of the material used for the optical waveguide 75, and d ≧ λ / n. Thereby, attenuation of light in the optical waveguide 75 can be suppressed. For example, when ZnS having a refractive index n of 2.37 is used and the light source wavelength λ is 405 nm, the film thickness d of the optical waveguide 75 is preferably 170 nm or more.

  Here, FIG. 20 is a cross-sectional view of the magnetic recording / reproducing head of FIG. As shown in FIG. 20, after the film is formed, the optical waveguide 75 is processed so that the lower part becomes thinner. Specifically, a resist pattern is formed on the optical waveguide 75, and regions other than the region where the optical waveguide 75 is left are removed by performing an etching process or a milling process.

  The width of the optical waveguide 75 shown in FIG. 20 is as wide as about 1 μm to 2 μm so that the light from the surface emitting laser light source 81 propagates efficiently in the upper part of the optical waveguide 75, and the light is narrowed and formed later in the lower part. In order to generate heat for heating the magnetoresistive effect element 70, the magnetoresistive effect element 70 is thinned to λ / n or less.

  The lower portion of the optical waveguide 75 is processed so that its width is equal to or smaller than the width of the recording bit to be read by the magnetoresistive element 70. Since the magnetoresistive effect element 70 has a width of a region where the coercive force is reduced by heating the magnetoresistive effect element 70 and the reproduction resolution in the track width direction is determined, the width below the optical waveguide 75 is the magnetic recording / reproducing head 71. The playback resolution in the track width direction is determined.

  It should be noted that the light introduced into the optical waveguide 75 may be entirely converted into heat in the region where the light is narrowed down to heat the magnetoresistive effect element 70, and a part of the light is irradiated onto the magnetic recording medium from the lower end. In addition to heating the magnetic recording medium, the magnetoresistive element 70 may be heated by the radiant heat.

Subsequently, an insulator 82 (see FIG. 20) having a lower refractive index than the material of the optical waveguide 75 is sputtered to the same height as the optical waveguide 75 on the lower magnetic shield 74 in the region where the optical waveguide 75 has been removed by the etching process. The resist is removed by the method, and the surface is flattened. Here, by forming the insulator 82 with a material having a lower refractive index than the material of the optical waveguide 75, the light propagating through the optical waveguide 75 is totally reflected at the interface with the insulator 82, and the light is transmitted to the insulator 82. Leakage can be prevented. For the insulator 82, Al ₂ O ₃ or SiO ₂ can be used.

Subsequently, a magnetoresistive element 70 is formed, and an insulating layer 76 made of Al ₂ O ₃ or SiO ₂ and an upper magnetic shield 77 made of NiFe are formed in order. The insulating layer 76 is formed with a film thickness of about 20 nm to 100 nm by sputtering. The upper magnetic shield 77 is formed with a film thickness of 1 μm to 3 μm using a sputtering method or a plating method.

Subsequently, after an insulator 83 made of Al ₂ O ₃ or SiO ₂ is formed, a thin film coil 78 made of Cu or Au is formed with a film thickness of 1 μm from the exposed side of the magnetoresistive effect element 70 using a resist pattern and a plating method. To 3 μm. After further forming an insulator 83 on the thin film coil 78, a contact hole reaching the upper magnetic shield 77 is formed at the center of the thin film coil 78 by etching, and a magnetic pole 79 made of NiFe is formed by sputtering.

  Subsequently, after processing the width of the magnetic pole 79 into a track width to be recorded by etching, an insulator 83 is further formed to cover the side surface of the magnetic pole 79. A transparent dielectric film 80 is formed on the head base 73 on which the reproducing unit and the recording unit are formed in this manner so as to be in contact with the optical waveguide 75. On the transparent dielectric film 80, the same material as that of the optical waveguide 75 is formed with a film thickness of about 100 nm to 400 nm on a part of or the entire upper surface of the head base 73.

  Subsequently, a surface emitting laser light source 81 is attached on the transparent dielectric film 80 to complete the magnetic recording / reproducing head 71.

  In the present embodiment, the surface emitting laser light source 81 is used, but an edge emitting laser light source may be used. In this embodiment, the surface emitting laser light source 81 is integrally formed with the magnetic recording / reproducing head 71. However, the surface emitting laser light source 81 or the edge emitting laser light source is provided on the suspension arm 133 shown in FIG. It is also possible to form the magnetic recording / reproducing head 71 by using a waveguide.

(Example 10)
Next, Example 10 according to the present invention will be described below. FIG. 21 discloses a magnetic recording / reproducing head suitable for optical (thermal) -assisted magnetic recording according to the tenth embodiment. The magnetic recording / reproducing head 91 of this embodiment has a configuration in which an optical waveguide 103 is formed between the magnetic pole 99 for recording and the insulator 102 in addition to the configuration of the magnetic recording / reproducing head 71 shown in the ninth embodiment. It has become. In addition, since the part of the codes | symbols 82-93 in Example 9 and the part of the codes | symbols 102-113 in Example 10 are the parts of the same structure in order, the description may be abbreviate | omitted.

  The optical waveguide 103 is for irradiating light from the surface emitting laser light source 101 toward the magnetic recording medium from the vicinity of the magnetic pole 99, and heats the magnetic recording medium to reduce the coercive force of the magnetic recording medium. This is for performing so-called light (heat) assist recording, which enables low magnetic field recording. The material and the forming method used for the optical waveguide 103 are the same as those of the optical waveguide 85 shown in the ninth embodiment.

  The manufacturing process of the magnetic recording / reproducing head 111 of the present embodiment is the same as the manufacturing process of the magnetic recording / reproducing head 71 shown in the ninth embodiment until the magnetic pole 99 is formed. 103 is formed by a sputtering method, and is processed so that the lower part is thin (the same shape as the optical waveguide 75 of FIG. 20 of the ninth embodiment) as with the optical waveguide 95. At this time, if the width of the lower end of the optical waveguide 103 is made smaller than the wavelength of the surface-emitting laser light source 101 as a light source (preferably 100 nm or less), near-field light (evanescent light) from the lower end of the optical waveguide 103 toward the magnetic recording medium. Light) and a region smaller than the light source wavelength can be heated, so that magnetic information can be recorded with high resolution.

  After the optical waveguide 103 is processed and formed, an insulator 102 is further formed to cover the side surface of the optical waveguide 103. The transparent dielectric film 100 is formed on the head base 93 on which the reproducing unit and the recording unit are formed in this manner so that the optical waveguide 95 and the optical waveguide 103 are in contact with each other. On the transparent dielectric film 100, the same material as that of the optical waveguide 95 and the optical waveguide 103 is formed with a film thickness of about 100 nm to 400 nm on a part or the entire surface of the head base 93.

  Subsequently, the surface emitting laser light source 101 is attached on the transparent dielectric film 100, and the magnetic recording / reproducing head 91 is completed. As the surface-emitting laser light source 101, for example, a GaN-based surface-emitting laser light source having a light source wavelength of about 405 nm is used in the same manner as the surface-emitting laser light source 81 of the ninth embodiment.

  The magnetic recording / reproducing head 91 formed in this way is a recording element (magnetic pole 99) and a reproducing element (one of the magnetoresistive effect elements of the above-described embodiments and examples) using a single light source. Light can be supplied from both the magnetoresistive element 90) and the vicinity. That is, it is possible to provide a magnetic recording / reproducing head suitable for light (heat) assisted recording using any one of the magnetoresistive effect elements of the above-described embodiments and examples.

  In the present embodiment, the surface emitting laser light source 101 is used, but an edge emitting laser light source may be used. In this embodiment, the surface emitting laser light source is integrally formed with the magnetic recording / reproducing head 91. However, the surface emitting laser light source 101 or the edge emitting laser light source is formed on the suspension arm 133 shown in FIG. However, it may be in a form of drawing light into the magnetic recording / reproducing head 91 using a waveguide.

(Example 11)
Next, Example 11 according to the present invention will be described below. FIG. 22 discloses a magnetic recording / reproducing head more suitable than the tenth embodiment for optical (thermal) assisted magnetic recording according to the eleventh embodiment. The magnetic recording / reproducing head 111 of this example, like the magnetic recording / reproducing head 91 shown in Example 10, is a magnetoresistive effect element 126 that is one of the magnetoresistive effect elements of the above-described embodiment and examples. The optical waveguide 115 and the optical waveguide 123 adjacent to the magnetic pole 119 for recording are formed respectively. However, the present embodiment is mainly different from the ninth embodiment in that the surface emitting laser light sources that supply light to the optical waveguide 115 and the optical waveguide 123 are the individual surface emitting laser light sources 121 and 125, respectively. In addition, since the site | part of the codes | symbols 92-103 in Example 10 and the site | parts of the codes | symbols 112-123 in Example 10 are each the site | parts of the same structure in order, the description may be abbreviate | omitted.

  23 is a cross-sectional view of the magnetoresistive effect element in FIG. As described above, in order to separate the light sources for supplying light to the optical waveguide 115 and the optical waveguide 123, the optical waveguide 115 and the optical waveguide 123 may be formed so as to be shifted as shown in FIG. Along with this, the magnetoresistive effect element 126, the magnetic pole 119, and the thin film coil 118 are also arranged at positions shifted from the center, and the transparent dielectric films 120 and 124 formed thereon are also shifted from the center so as not to contact each other. To do. If the surface emitting laser light sources 121 and 125 are formed on the transparent dielectric films 120 and 124 formed so as to be shifted from the center in this way, light is supplied independently to the optical waveguide 115 and the optical waveguide 123 from the individual light sources. The configuration can be realized.

  As described above, when light is supplied from separate light sources to the recording element (magnetic pole 119) and the reproducing element (magnetoresistance effect element 126), the optimum light quantity for the recording element and the optimum light quantity for the reproducing element Can be individually controlled, and a magnetic recording / reproducing head capable of recording / reproducing with higher resolution can be provided.

  Here, as the surface emitting laser light sources 121 and 125, for example, a GaN-based surface emitting laser light source having a light source wavelength of about 405 nm is used as in the surface emitting laser light source 81 of the ninth embodiment and the surface emitting laser light source 101 of the tenth embodiment. . The transparent dielectric films 120 and 124 can be made of the same material as the transparent dielectric film 80 of Example 9 and the transparent dielectric film 100 of Example 10 with the same film thickness.

  In this embodiment, the surface emitting laser light sources 121 and 125 are used. However, an edge emitting laser light source may be used. In this embodiment, the surface emitting laser light sources 121 and 125 are integrally formed with the magnetic recording / reproducing head 111. However, the surface emitting laser light sources 121 and 125 or the end surfaces are formed on the suspension arm 133 shown in FIG. A light emitting laser light source may be formed and light may be drawn into the magnetic recording / reproducing head 111 using a waveguide.

(Example 12)
Next, Example 12 according to the present invention will be described below. FIG. 24 shows a configuration diagram of a magnetic information recording / reproducing apparatus according to Example 12 using the magnetic recording / reproducing heads shown in Examples 9 to 11.

  The magnetic information recording / reproducing apparatus 130 rotates a suspension arm 133 attached to a drive unit 132 using a voice coil motor 131, a magnetic recording / reproducing head 134 attached to the tip of the suspension arm, a magnetic recording medium 137, and a magnetic recording medium 137. It comprises a spindle 135 and a control circuit 136. The magnetic recording / reproducing heads 71, 91, and 111 shown in the ninth to eleventh embodiments can be applied to the magnetic recording / reproducing head 134.

  Further, the control circuit 136 includes a signal processing device for exchanging signals with the magnetic recording / reproducing head 134, a light source formed on the magnetic recording / reproducing head 134 (surface emitting laser light sources 81, 101, 121 shown in the ninth to twelfth embodiments). , 125), and a memory device for storing the read information.

  Next, FIG. 25 shows an operation process procedure of the magnetic information reproducing method using the magnetic information recording / reproducing apparatus shown in FIG. When the power is turned on, first, the spindle 135 rotates to rotate the magnetic recording medium 137 (step S1). Subsequently, a part of the magnetoresistive effect element formed on the magnetic recording / reproducing head 134 is heated by a light source (surface emitting laser light source) formed on the magnetic recording / reproducing head 134 directly or by radiant heat obtained by heating the magnetic recording medium 137. (Step S2). At this time, the output control means included in the control circuit 136 adjusts the output of the light source so as to obtain good reproduction signal quality. Subsequently, the drive unit 132 moves the magnetic recording / reproducing head 134 onto the address information recording area recorded in advance on the magnetic recording medium 137, and the leakage magnetic field from the address information recording area is changed to a magnetic resistance in the magnetic recording / reproducing head 134. The address information is read by detecting the effect element (step S4). Subsequently, based on the read address information, the magnetic recording / reproducing head 134 is moved onto the information recording area where the magnetic recording information to be read is recorded (step S5), and the leakage magnetic field from the information recording area is reduced. Magnetic recording information is read by detection by the magnetoresistive element in the magnetic recording / reproducing head 134 (step S6). Then, the reproduction of magnetic information ends.

  When reproducing the address information and magnetic recording information, a part of the magnetoresistive effect element in the magnetic recording / reproducing head 134 is always heated to a certain temperature or more by the light source. That is, it is important that the light source (surface emitting laser light source) heats a part of the magnetoresistive effect element prior to the reproduction of the address information and the magnetic recording information (that is, detection of the leakage magnetic field from the magnetic recording medium 137).

  The present invention can be changed in design without departing from the scope of the claims, and is not limited to the above-described embodiments and examples. For example, the reproducing magnetic sensor according to the present invention may be a magnetic sensor for detecting a leakage magnetic field from a magnetic recording medium, or a magnetic sensor for detecting geomagnetism for use in an electronic compass. Good. Further, it may be a magnetic sensor for use in a rotary encoder, linear encoder, or position detection sensor.

It is a figure which shows the relationship between the temperature change of the magnetization amount in the ferrimagnetic material layer containing a rare earth metal and a transition metal, and the temperature change of a coercive force, and the magnetization direction of the ferrimagnetic material layer corresponding to these. It is a figure which shows a mode that the curve of a coercive force changes with the metal composition ratio in the material containing a some transition metal. It is typical sectional drawing which shows the film | membrane structure of the magnetoresistive effect element which concerns on one embodiment of this invention. FIG. 4 is a schematic cross-sectional view showing a film configuration of a modified example of the magnetoresistive effect element in FIG. 3. It is a characteristic view showing the measurement result of MR ratio of the magnetoresistive effect element of comparative example 1, and (a) is 25 ° C and (b) is in 150 ° C. It is a characteristic view showing the measurement result of MR ratio of the magnetoresistive effect element of Example 1 concerning the present invention, and (a) is 25 ° C and (b) is in 150 ° C. It is a characteristic view showing the relationship between the temperature and MR ratio of the magnetoresistive effect element of Example 1 and Comparative Example 1. It is a characteristic view showing the result of having measured the relationship between the temperature and MR ratio of the magnetoresistive effect element of Example 1 which concerns on this invention in a different magnetic field range. 6 is a graph showing the results of measuring the magnetic properties (MH loop) of a ferrimagnetic layer used in the magnetoresistive effect element of Example 1; It is a figure which shows the result of MR ratio which measured MR ratio of the magnetoresistive effect element of Example 1 and 5 with respect to an external magnetic field in the state which heated the magnetoresistive effect element to 150 degreeC with the heater. It is typical sectional drawing which shows the film | membrane structure of the magnetoresistive effect element of Example 5 which concerns on this invention. FIG. 10 is a characteristic diagram showing the MR ratio of the magnetoresistive element of Example 5. It is typical sectional drawing which shows the film | membrane structure of the magnetoresistive effect element used for the magnetic sensor for reproduction | regeneration of Example 6 which concerns on this invention. FIG. 10 is a schematic diagram showing the relationship among a reproducing magnetic sensor, a heating temperature raising region, and a magnetic recording medium in Example 6. FIG. 10 is a characteristic diagram showing the relationship between the track width and the output voltage of the reproducing magnetic sensor of Example 6. An aperture plate used to generate near-field light used when heating a magnetoresistive effect element, wherein (a) and (b) are micro openings, and (c) and (d) are micro projections. It is a figure which shows the opening which has. It is a characteristic view showing the relationship between the track width and output voltage of the magnetic sensor for reproduction of Examples 7 and 9 according to the present invention. It is a perspective view which shows the other arrangement | positioning of the reproduction | regeneration magnetic sensor, heating temperature rising area, and magnetic recording medium of the modification of Example 8 which concerns on this invention. It is a schematic diagram which shows the structure of the magnetic head for recording / reproducing of Example 9 based on this invention. FIG. 20 is an AA cross-sectional arrow view of the recording / reproducing magnetic head shown in FIG. 19. It is a schematic diagram which shows the structure of the magnetic head for recording / reproducing of Example 10 based on this invention. It is a schematic diagram which shows the structure of the magnetic head for recording / reproducing of Example 11 based on this invention. FIG. 23 is a cross-sectional view of the magnetic head for recording / reproducing shown in FIG. It is a block diagram which shows the magnetic recording / reproducing apparatus of Example 12 based on this invention. 18 is a flowchart showing a reproducing procedure of the magnetic recording / reproducing apparatus in Example 12. It is typical sectional drawing of the conventional magnetoresistive effect element.

Explanation of symbols

1, 2, 201 Substrate 2, 22, 32, 202 Lower electrode layer 3, 23, 203 Magnetization fixed layer 3a, 23a, 203a Antiferromagnetic layer 3b, 203b Ferromagnetic layer 4, 24, 204 Nonmagnetic layer 5, 15, 23b, 35 Ferrimagnetic material layers 6, 16, 26, 36, 206 Upper electrode layers 7, 17, 27, 37, 51 In-plane magnetic layers 10, 20, 30, 40, 42, 52, 70, 90, 200 Magnetoresistive element 18, 28, 38 High permeability layer 25, 205 Magnetization free layer 39, 82, 83, 102, 209 Insulator 41, 210 Permanent magnet 43, 53 Heating temperature rising region 44, 54, 137 Magnetic recording Medium 45 Electrode 46 Base 47, 74 Lower magnetic shield 48, 77 Upper magnetic shield 49 Heating means 49a Semiconductor laser light source 49b Lens 50, 60 Reproducing magnetic sensor 71, 91 111, 134 Magnetic recording / reproducing head 72 Air bearing surface 73, 93 Head base 75, 85, 95, 103, 115, 123 Optical waveguide 76 Insulating layer 78, 118 Thin film coil 79, 99, 119 Magnetic pole 80, 100, 120 Transparent dielectric Body film 81, 101, 121, 125 Surface-emitting laser light source 130 Magnetic information recording / reproducing device 131 Voice coil motor 132 Drive unit 133 Suspension arm 135 Spindle 136 Control circuit

Claims (26)

A magnetoresistive element having a nonmagnetic layer and two magnetic layers sandwiching the nonmagnetic layer and obtaining a magnetoresistance change by a relative angular change in the magnetization direction of the two magnetic layers,
At least one of the two magnetic layers includes a ferrimagnetic layer formed of two or more kinds of magnetic bodies having antiparallel magnetization directions, and the ferrimagnetic layer changes with temperature. A magnetoresistive effect element characterized in that the coercive force of a body layer changes. A magnetoresistive element having a nonmagnetic layer and two magnetic layers sandwiching the nonmagnetic layer and obtaining a magnetoresistance change by a relative angular change in the magnetization direction of the two magnetic layers,
At least one of the two magnetic layers includes a ferrimagnetic layer formed of two or more kinds of magnetic bodies having antiparallel magnetization directions, and the ferrimagnetic layer changes with temperature. A magnetoresistive effect element, wherein a magnetization angle of the ferrimagnetic material layer with respect to a layer forming surface of the body layer changes.   3. The magnetoresistive effect element according to claim 1, wherein a magnetoresistive effect ratio larger than a magnetoresistive effect ratio at the temperature T1 is obtained at a temperature T2 higher than a certain temperature T1.   The magnetoresistive effect element according to claim 1, wherein a magnetoresistive effect ratio larger than a magnetoresistive effect ratio at room temperature is obtained at a temperature higher than room temperature.   5. The coercive force difference is generated between a heated region and a non-heated region of the ferrimagnetic material layer by heating a part of the magnetoresistive effect element. The magnetoresistive effect element according to item.   6. The magnetoresistive element according to claim 5, wherein a coercive force of the ferrimagnetic material layer is smaller in the heating region than in the non-heating region.   When a part of the magnetoresistive effect element is heated, a difference in magnetization angle with respect to the layer forming surface of the ferrimagnetic layer occurs between the heated region and the non-heated region of the ferrimagnetic layer. The magnetoresistive effect element according to any one of claims 1 to 6.   8. The magnetoresistive effect element according to claim 7, wherein a magnetization angle of the ferrimagnetic layer with respect to a layer forming surface is smaller in the heating region than in the non-heating region. The two magnetic layers are a magnetization fixed layer, and a magnetization free layer whose magnetization direction changes with a magnetic field smaller than a magnetic field when the magnetization direction of the magnetization fixed layer changes,
The magnetoresistive effect element according to claim 1, wherein the magnetization free layer includes the ferrimagnetic material layer.   The ferrimagnetic layer includes at least one heavy rare earth metal element selected from Tb, Gd, Dy, and Ho and at least one 3d transition metal element selected from Fe, Co, and Ni. The magnetoresistive effect element according to any one of claims 1 to 9, wherein The ferrimagnetic layer includes a heavy rare earth metal element and a 3d transition metal element;
The magnetoresistive element according to any one of claims 1 to 10, wherein the heavy rare earth metal element is Gd, and the 3d transition metal element is Co, Fe, or Co. The 3d transition metal element includes Fe and Co;
The magnetoresistive effect element according to claim 10 or 11, wherein the composition ratio of Fe and Co is equal, or the composition ratio of Co to Fe is large.   An in-plane magnetic layer having a magnetization direction substantially parallel to a layer forming surface of the ferrimagnetic layer is formed between the ferrimagnetic layer and the nonmagnetic layer. Item 13. The magnetoresistive effect element according to any one of Items 1 to 12.   14. The in-plane magnetization layer having a higher magnetic permeability than the ferrimagnetic layer is formed in contact with or magnetically coupled to the ferrimagnetic layer. 2. A magnetoresistive element according to item 1.   The magnetic sensor provided with the magnetoresistive effect element of any one of Claims 1-14, and the electrode for applying an electric current to the said magnetoresistive effect element. A magnetic sensor comprising the magnetoresistive effect element according to claim 1, an electrode for applying a current to the magnetoresistive effect element, and a heating unit for heating the magnetic sensor. And
A reproducing head characterized in that the heating means raises the temperature of the ferrimagnetic material layer.   The reproducing head according to claim 16, wherein the heating unit is a light source. A reproduction head according to claim 16 or 17, and a magnetic recording medium,
The magnetic information reproducing apparatus, wherein the heating means heats the ferrimagnetic material layer.   19. The magnetic information reproducing apparatus according to claim 18, wherein a surface perpendicular to the stacking direction of the magnetoresistive effect elements is inclined with respect to the surface of the magnetic recording medium.   17. A composite head comprising: the reproducing head according to claim 16; and a recording head for recording magnetic information by applying a magnetic field to the magnetic recording medium.   18. A reproducing head according to claim 17, and a recording head for recording magnetic information by applying a magnetic field to a magnetic recording medium, wherein the recording head uses near-field light. Composite head.   The composite head according to claim 21, wherein the light source is also used as a light source of the near-field light.   A magnetic information recording / reproducing apparatus comprising the composite head according to any one of claims 20 to 22.   A magnetic information reproducing apparatus comprising the reproducing head according to claim 16. A magnetoresistive element having a nonmagnetic layer and two magnetic layers sandwiching the nonmagnetic layer, and obtaining a magnetoresistance change by a relative angular change in the magnetization direction of the two magnetic layers; and A reproducing method for reproducing magnetic information recorded on a magnetic recording medium using a reproducing head in which an electrode for applying a current to a magnetoresistive element is formed,
At least one of the two magnetic layers includes a ferrimagnetic layer formed of two or more kinds of magnetic bodies having antiparallel magnetization directions, and the ferrimagnetic layer changes with temperature. The coercivity of the body layer changes,
A magnetic information reproducing method, wherein magnetic information is reproduced in a state where the ferrimagnetic material layer is heated by heating.   26. The method for reproducing magnetic information according to claim 25, wherein the ferrimagnetic material layer is heated in advance prior to reproducing the recorded information recorded on the magnetic recording medium.

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