JP2006338719A - Magnetic head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spin valve magnetic head of a configuration which can satisfy both the high level and stability of a reproduced output. <P>SOLUTION: The spin valve magnetic head has a magnetic domain control structure where a first and a second antiferromagnetically coupled magnetic domain control layers 19 and 21 both having the same magnetization are stacked on a soft magnetic free layer 17, and can make both the high output level and stabilization. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic head mounted on a magnetic recording / reproducing apparatus, and more particularly to a magnetic head for a high recording density magnetic recording / reproducing apparatus.

  The magnetoresistive head is used as a reproduction sensor in high recording density magnetic recording technology mainly for hard disks, and is a part that greatly affects the performance of magnetic recording technology. In recent years, it is well known that the magnetoresistive effect, that is, the so-called giant magnetoresistance (GMR) effect of a multilayer film in which a ferromagnetic metal layer is laminated via a nonmagnetic metal layer is large. In this case, the electric resistance varies depending on the magnetization of the two ferromagnetic layers sandwiching the nonmagnetic intermediate layer and the angle formed by the magnetization. When this giant magnetoresistance effect is used in a magnetoresistive element, a structure called a spin valve has been proposed. The spin valve has an antiferromagnetic layer / ferromagnetic layer / nonmagnetic intermediate layer / ferromagnetic layer structure and is in contact with the antiferromagnetic layer by an exchange coupling magnetic field generated at the interface of the antiferromagnetic layer / ferromagnetic layer. The output can be obtained by substantially fixing the magnetization of the ferromagnetic layer and rotating the magnetization of the other ferromagnetic layer freely by an external magnetic field. The ferromagnetic layer whose magnetization is substantially fixed by the antiferromagnetic layer is called a ferromagnetic fixed layer, and the ferromagnetic layer whose magnetization is rotated by an external magnetic field is called a soft magnetic free layer.

  The above basic configuration is common to GMR currently used for applications, specifically CIP-GMR, tunnel magnetoresistive element so-called TMR, and vertical conduction type GMR so-called CPP-GMR. Therefore, the configuration of the present invention relates to CIP-GMR, TMR, and CPP-GMR, and is particularly effective for perpendicular current type magnetoresistive effect sensors of CPP-GMR and TMR. In the reproduction sensor, a pair of magnetic shields are provided so as to sandwich the magnetoresistive element in order to select a magnetic field to be sensed from all external magnetic fields.

  The magnetoresistive effect type magnetic head has a magnetic domain control structure for making the soft magnetic free layer into a single magnetic domain. This magnetic domain control structure has a function of setting the soft magnetic free layer to a single magnetic domain state and providing an output having no hysteresis with respect to the magnetic field to be sensed. A structure called a hard bias is known as a typical magnetic domain control structure. Furthermore, a laminated magnetic domain control structure has been proposed as a magnetic domain control structure corresponding to a high recording density. In the laminated magnetic domain control structure, a single-domain ferromagnetic antiparallel layer, which becomes the magnetic domain control film, is laminated on the magnetoresistive effect film and formed to have approximately the same track width, thereby forming aligned edges. In addition, the magnetic domain control is performed.

  In the spin valve using the laminated magnetic domain control, a structure composed of a soft magnetic free layer / weakly antiparallel coupling layer / single domained ferromagnetic antiparallel layer / single domained antiferromagnetic layer has been proposed (Patent Literature). 1, 2). In this type of magnetic domain control, the single-domain antiferromagnetic layer and the single-domain antiferromagnetic layer are antiferromagnetically coupled, and the single-domain antiferromagnetic layer becomes a single domain, and the single-domain antiferromagnetic layer The layer is coupled to the soft magnetic free layer via the weak antiparallel coupling layer, substantially the same or smaller than the magnetic field to be sensed by magnetostatic coupling or antiferromagnetic coupling, and single domained ferromagnetic antiparallel The layer and the soft magnetic free layer form a closed magnetic path, and the soft magnetic free layer has a single magnetic domain.

  On the other hand, a structure that does not use a single-domain antiferromagnetic film has been proposed (Patent Document 3) and has the following configuration. This is a structure comprising a ferromagnetic pinned layer / nonmagnetic intermediate layer / soft magnetic free layer / weak antiparallel coupling layer / ferromagnetic parallel layer / strong antiparallel coupling layer / ferromagnetic antiparallel layer. The ferromagnetic antiparallel layer is antiferromagnetically coupled through a strong antiparallel coupling layer and is substantially fixed to the magnetic field to be sensed, and the ferromagnetic antiparallel layer is coupled through a weak antiparallel coupling layer. A soft magnetic free layer, a ferromagnetic antiparallel layer, and a ferromagnetic parallel layer that are substantially the same or smaller than the magnetic field to be sensed by a magnetostatic coupling or an antiferromagnetic coupling. In this structure, the closed magnetic circuit is configured so that the sum of the magnetizations of the magnetic field becomes substantially zero, and the soft magnetic free layer is made into a single magnetic domain. (1) A single-domain ferromagnetism and a ferromagnetic parallel layer having a predetermined magnetic anisotropy have a role of fixing the magnetization direction. (2) A closed magnetic circuit structure with three layers including a soft magnetic layer. Thus, the demagnetizing field is reduced, and the deviation of the magnetization of the ferromagnetic antiparallel layer and the ferromagnetic parallel layer from a predetermined direction due to the external magnetic field is prevented.

JP 2002-367124 A U.S. Patent No. 6,473,279 JP 2002-025013 A

  In a conventional magnetoresistive effect sensor having a laminated magnetic domain control structure, it is difficult to realize a read head using a spin valve magnetoresistive effect element that satisfies all of higher recording density, higher output, and stable operation. The problem with the above-mentioned laminated magnetic domain control structure (Patent Documents 1 and 2) is that the total thickness of the magnetoresistive effect element is larger than that of the hard bias structure due to the single-domain antiferromagnetic layer. Since the size is increased by about 10 to 20 nm, the interval between the magnetic shields is widened, which makes it difficult to read at a high recording density. In addition, since the overall resistance of the magnetoresistive effect element is increased by the single-domain antiferromagnetic layer, the resistance change apparently caused by the change in the angle between the magnetization of the soft magnetic free layer and the magnetization of the ferromagnetic pinned layer is apparent. However, there is a problem that the output is reduced.

  On the other hand, the problem of the laminated magnetic domain control structure that does not use a single-domain antiferromagnetic film (Patent Document 3) is that the total magnetization of the three layers of the soft magnetic free layer, the ferromagnetic antiparallel layer, and the ferromagnetic parallel layer is substantially In other words, it has a closed magnetic circuit structure in which the sum of the magnetization of the soft magnetic free layer and the magnetization of the ferromagnetic antiparallel layer is approximately equal to the magnetization of the ferromagnetic parallel layer. This is because, as a reaction of stabilizing by configuring a closed magnetic circuit with the above three layers, the magnetization amount of the two layers of the ferromagnetic antiparallel layer and the ferromagnetic parallel layer must be unequal. It is. As a result, there is room for improvement in the function of fixing the magnetization of the ferromagnetic antiparallel layer and the ferromagnetic parallel layer to be substantially fixed with respect to the magnetic field to be sensed.

  An object of the present invention is to provide a magnetic head satisfying all of high recording density reading, high output, and high stability.

  The present invention uses the following configuration in order to achieve the object. (1) As a magnetic domain control structure of the soft magnetic free layer, a first antiparallel coupling layer, a first magnetic domain control layer, a second antiparallel coupling layer, and a second magnetic domain control layer are formed on the soft magnetic free layer. Adopt a laminated structure. (2) The soft magnetic free layer and the first magnetic domain control layer are stacked via the first antiparallel coupling layer, and are configured so that their magnetizations are arranged antiparallel. Similarly, the second magnetic domain control layer and the first magnetic domain control layer are stacked via the second antiparallel coupling layer so that their magnetizations are arranged antiparallel. (3) When the absolute values of the magnetization amounts of the soft magnetic free layer, the first magnetic domain control layer, and the second magnetic domain control layer are M1, M2, and M3, M2 and M3 are approximately M2 = M3. Thus, the film thickness is set to be almost the same. Of course, the amount of magnetization M1 of the soft magnetic free layer is M1> 0.

  As a result of the above (1), (2) and (3), the track end portion of the element laminated portion formed with substantially the same track width corresponding to the predetermined magnetic sensitive width is incomplete so that (M1−M2 + M3)> 0. A closed magnetic circuit structure can be realized.

  As a result, the first magnetic domain control layer and the second magnetic domain control layer realize a local closed magnetic circuit in which M3−M2≈0, and the stable magnetization state in which the magnetization does not fluctuate or change with respect to the magnetic field to be sensed. And the first magnetic domain control layer can be magnetically coupled to the soft magnetic free layer to make the soft magnetic free layer into a single magnetic domain.

  According to the present invention, the first magnetic domain control layer and the second magnetic domain control layer having the same magnetization amount and the second magnetic domain control layer are antiferromagnetically coupled to each other. Can realize a structure in which the magnetization of the magnetic domain control layer is substantially fixed, and can stably control the magnetization of the soft magnetic free layer by magnetically coupling with a ferromagnetic antiparallel layer in a stable magnetization state. Thus, a magnetoresistive effect type magnetic sensor having both high stability and output can be realized. Also, in a magnetic recording / reproducing apparatus using this sensor as a reproducing head, a high recording density, that is, a recording wavelength recorded on a recording medium is short, and recording with a narrow recording track is realized, and sufficient reproducing output is achieved. And good recording can be maintained.

  In the present invention, in order to provide a magnetic recording device in which a magnetic sensor using a giant magnetoresistive effect corresponding to a high recording density is mounted on a magnetic head, the magnetic sensor is an antiferromagnetic film / ferromagnetic fixed layer / non-magnetic film. A magnetoresistive effect element having a laminated structure of magnetic intermediate layer / soft magnetic free layer / first antiparallel coupling layer / first magnetic domain control layer / second antiparallel coupling layer / second magnetic domain control layer is used. Here, the antiferromagnetic film applies an exchange coupling bias for substantially fixing the magnetization of the ferromagnetic pinned layer, and is formed in close contact with the ferromagnetic pinned layer, or indirectly magnetically. The effect may be brought about through a mechanical bond. Alternatively, instead of the antiferromagnetic film, other bias applying means, for example, residual magnetization of a hard magnetic film or current bias may be used.

  The first antiparallel coupling layer has a function of generating a weak magnetic coupling that causes antiparallel coupling between the first magnetic domain control layer and the soft magnetic free layer. Here, the weak coupling means having the same order of magnitude or weak coupling force with respect to the magnetic field to be sensed. That is, when the magnetic field is near zero, the magnetizations of the soft magnetic free layer and the first magnetic domain control layer are antiparallel to each other, and the soft magnetic free layer and the first magnetic domain control layer That is, it has a binding force that changes the angle between the magnetizations of each other. Specifically, it is configured to have an antiparallel coupling magnetic field of about several tens to several hundreds Oersted. As a result, the magnetization direction of the soft magnetic free layer is maintained in the single magnetic domain state by the application of the magnetic field to be sensed, and the magnetization direction rotates along the applied magnetic field direction. The function of having sensitivity can be achieved at the same time.

  With the magnetic domain control configuration described above, the magnetization state of the laminated magnetic domain control of the present invention is such that when the magnetic field is near zero, the magnetization states of the second magnetic domain control layer, the first magnetic domain control layer, and the soft magnetic free layer are adjacent to each other. The magnetizations of each other have antiparallel magnetization states.

  The soft magnetic free layer, the first anti-parallel coupling layer, the first magnetic domain control layer, the second anti-parallel coupling layer, and the second magnetic domain control layer are processed and formed to have substantially the same track width and are substantially at the same position. The first magnetic domain control layer generates magnetization by the track width direction residual magnetization, and the soft magnetic free layer and the second magnetic domain control layer have residual magnetization in the track width direction at the track width direction end. And magnetostatically coupled to each other, the effect of making the soft magnetic free layer into a single magnetic domain can be obtained. The magnetization of the ferromagnetic pinned layer is oriented substantially parallel to the direction of the magnetic field to be sensed, and the magnetization of the first magnetic domain control layer is oriented substantially perpendicular to the direction of the magnetic field to be sensed.

  By realizing the configuration as described above, the magnetic sensor of the present invention can define the magnetization state in a narrow sensor size, and can realize a stable operation.

  Hereinafter, the present invention will be described specifically by way of examples. The thin film constituting the giant magnetoresistive layered film of the present invention is produced by sequentially laminating the following materials on a ceramic substrate in a 1 to 6 millitorr (0.1 to 0.8 Pascal) atmosphere of argon by a DC magnetron sputtering apparatus. did. As sputtering targets, tantalum, nickel-20at% iron alloy, copper, Co-Fe, MnPt, ruthenium, alumina, magnetite, and MnIr targets were used. In the laminated film, high frequency power was applied to each cathode on which each target was placed to generate plasma in the apparatus, and each layer was sequentially formed by opening and closing the shutters placed on each cathode one by one. During film formation, a permanent magnet was used to apply a magnetic field of approximately 80 oersted (6.4 kA / m) parallel to the substrate to provide uniaxial anisotropy. The formed film was heat-treated in a magnetic field at 270 ° C. for 3 hours in a vacuum to transform the phase of the MnPt antiferromagnetic film, and the magnetoresistance at room temperature was measured and evaluated. Element formation on the substrate was patterned by a photoresist process. Thereafter, the substrate was processed with a slider and mounted on a magnetic recording apparatus.

  In addition, in order to evaluate the configuration of the magnetic domain control structure, a magnetization process simulation using the LLG (Landau-Lifschitz-Gilbert) method was performed, and the stability and output of the magnetic head were compared and examined.

  FIG. 1 is a diagram showing an example of the configuration of a vertical energization type giant magnetoresistive magnetic head according to the present invention. The figure is a schematic view seen from the facing surface facing the magnetic medium. The lower electrode 43 is formed on the substrate 50, the lower magnetic shield 41 is formed thereon, the magnetoresistive film 10 is formed thereon, and the upper magnetic shield 42 is further formed to form a reproduction gap. ing. An upper electrode 44 is formed on the upper magnetic shield 42. In the structure of FIG. 1, the lower electrode 43 can be shared by the lower magnetic shield 41. The upper electrode 44 can also be used as the upper magnetic shield 42.

  FIG. 2 is a diagram showing a configuration example of the present giant magnetoresistance effect type magnetic head of the in-plane energization method of the invention. The figure is a schematic view seen from the facing surface facing the magnetic medium. A lower magnetic shield 41 is formed on the substrate 50, a lower insulating layer 71 is formed thereon, a magnetoresistive film 10 is formed thereon, and electrodes 45 are formed on both ends of the magnetoresistive film 10. An upper insulating layer 72 is formed thereon, and an upper magnetic shield 42 is further formed to form a reproduction gap.

  The magnetoresistive film 10 in FIGS. 1 and 2 has the following configuration. That is, the underlayer 11, the antiferromagnetic film 12, the ferromagnetic pinned layer 31, the nonmagnetic intermediate layer 16, the soft magnetic free layer 17, the first antiparallel coupling layer 18, the first magnetic domain control layer 19, and the second The antiparallel coupling layer 20 and the second magnetic domain control layer 21 are continuously formed. The protective film 22 contributes to improvement of corrosion resistance and the like, but even if omitted, it does not violate the gist of the present invention. The underlying film 11 contributes to improvement of crystallinity, resistance change rate and soft magnetic characteristics, but even if omitted, it does not violate the gist of the present invention.

  In this configuration example, the ferromagnetic pinned layer 31 includes a laminated body of the first ferromagnetic film 13, the antiparallel coupling film 14, and the second ferromagnetic film 15. The antiparallel coupling film 14 applies exchange coupling that causes the magnetizations of the first ferromagnetic film 13 and the second ferromagnetic film 15 to be arranged in antiparallel with each other, thereby reducing the amount of substantial magnetization of the ferromagnetic fixed layer. This has the effect of controlling the difference in the amount of magnetization between the first ferromagnetic film 13 and the second ferromagnetic film 15. Here, it is not contrary to the gist of the present invention to form the ferromagnetic pinned layer 31 from a single-layer magnetic body or from a laminate of two layers or four layers or more. The example is effective for improving the symmetry of the signal waveform output from the magnetic sensor. The soft magnetic free layer 17 can be regarded as a magnetically integrated structure even if it is formed from a single-layer magnetic material or formed from a laminate of two or more layers although not shown in the figure. This is not against the gist of the invention.

  The soft magnetic free layer 17 of the magnetoresistive effect laminated film 10, the first antiparallel coupling layer 18, the first magnetic domain control layer 19, the second antiparallel coupling layer 20, and the second magnetic domain control layer laminated thereon. 21 is formed to have substantially the same size in the track width direction.

  The film thickness and material are selected so that the magnetization amounts of both the first magnetic domain control layer 19 and the second magnetic domain control layer 21 are equal. For example, although the case where the material which comprises the 1st magnetic domain control layer 19 and the 2nd magnetic domain control layer 21 is the same is the easiest embodiment, in this case, the film thickness of both is made equal. FIG. 3 shows a schematic diagram of the magnetization arrangement. When the magnetization amount of the soft magnetic free layer 17 is M1, the magnetization amount of the first magnetic domain control layer 19 is M2, and the magnetization amount of the second magnetic domain control 21 is M3, M2≈M3, that is, M3−M2≈0. To do. As a result, the magnetizations of the first magnetic domain control layer 19 and the second magnetic domain control 21 form a local closed magnetic circuit at the track end (the end in the left-right direction in the figure). It is possible to generate an effect that a change in magnetization is hardly caused by a magnetic field. On the other hand, the magnetization M1 of the soft magnetic free layer 17 is antiparallel to the magnetization M2 of the first magnetic domain control layer 19, and has an effect that the mutual magnetizations cancel each other at the track width end. Naturally, M1> 0, and the total magnetization of the three layers of the soft magnetic free layer 17, the first magnetic domain control layer 19, and the second magnetic domain control layer 21 is a total of (M1−M2 + M3)> 0. Forms an incomplete closed magnetic circuit with load.

Thus, for M1 and M2 and M2 and M3, a structure that locally cancels each other's end magnetic charges is realized, and overall, (M1−M2 + M3)> 0 end end magnetic charges are generated. The present invention realizes a configuration that forms a completely closed magnetic circuit. As an example, when a CoFe alloy having a saturation magnetization of 1400 emu / cm ³ (1.8 Tesla) is used for both the first magnetic domain control layer 19 and the second magnetic domain control layer 21, the first magnetic domain control layer 19 The film thickness of the second magnetic domain control layer 21 is preferably 3 nm. At this time, the amount of magnetization of the soft magnetic free layer 17 does not necessarily have to be equal to that of the first magnetic domain control layer 19 and the second magnetic domain control layer 21, and therefore the material / film thickness that maximizes the output can be selected. Is possible. For example, a total film thickness of 3.5 nm is obtained by stacking a CoFe alloy (saturation magnetization 1400 emu / cm ³ (1.8 Tesla)) on a NiFe alloy (saturation magnetization 800 emu / cm ³ (1 Tesla)) with a thickness of 2.5 nm. A laminate of the above is preferred.

  The second antiparallel coupling layer 20 is an in-plane antiferromagnetic coupling between the first magnetic domain control layer 19 and the second magnetic domain control layer 21 that are in contact with each other via the second antiparallel coupling layer 20. Therefore, a specific material is formed with a specific thickness, and is made of a material that does not have spontaneous magnetization at room temperature and the operating temperature of the magnetic head. For materials such as Ru, Ir, Cr, Rh, Re, Os, and Pt, the first magnetic domain control layer 19 and the second magnetic domain via the second antiparallel coupling layer 20 can be selected by appropriately selecting the thickness. Strong antiferromagnetic coupling can be generated between the control layers 21 in a plane. The magnitude of the antiferromagnetic coupling reaches several kilo-Oersted, that is, several hundred kA / m. In the second antiparallel coupling layer 20 of the present invention, it is desirable that the antiferromagnetic coupling is 1 kiloOersted or more, that is, a strong antiferromagnetic coupling of 80 kA / m or more. The bonding layer 20 is preferably made of a material such as Ru described above with a predetermined thickness of 0.2 to 1.0 nm.

  The first antiparallel coupling layer 18 generates in-plane weak antiferromagnetic coupling between the soft magnetic free layer 17 and the first magnetic domain control layer 19. The first antiparallel coupling layer 18 generates a weak magnetic exchange coupling between the soft magnetic free layer 17 and the first magnetic domain control layer 19 so that both the soft magnetic free layer 17 and the first magnetic domain control layer 19 Is weak and antiferromagnetically coupled, that is, a function of realizing an antiparallel magnetization arrangement state in a zero magnetic field is generated. However, the first antiparallel coupling layer 18 of the present invention desirably has a weaker effect than the second antiparallel coupling layer 20 described above. This is because it is necessary to appropriately adjust the coupling force so that the magnetization of the soft magnetic free layer 17 rotates relative to the magnetic field to be sensed to generate a reproduction signal. Specifically, materials such as Ru, Ir, Cr, Rh, Re, Os, and Pt with a thickness of 0.2 to 1.0 nm, and materials such as Cu, Au, Ag, Ta, and Ti with a thickness of 0.3 to 0.6 nm By using a laminated body of laminated layers, anti-parallel coupling with a predetermined strength of 100 to 600 Oersted (8 to 48 kA / m) can be realized.

  With such a configuration, the magnetizations of the first magnetic domain control layer 19 and the second magnetic domain control layer 21 are antiferromagnetically coupled via the second antiparallel coupling layer 20, and the first magnetic domain control layer 19 and The soft magnetic free layer 17 and the first magnetic domain control layer are fixed in the track width direction so as to be antiparallel to each other by the magnetostatic coupling due to the magnetic charge generated at the end of the second magnetic domain control layer 21. Magnetization of 19 through antiferromagnetic coupling through the first antiparallel coupling layer 18, and magnetostatic coupling due to the magnetic charge generated at the ends of the soft magnetic free layer 17 and the first magnetic domain control layer 19, When the magnetic fields to be sensed are zero, the soft magnetic free layer can be stably made into a single magnetic domain by coupling so that they are antiparallel to each other.

  In FIG. 1, the distance between the upper and lower magnetic shields on both sides in the track width direction of the element is configured to be narrower than the reproduction gap 10, and the so-called side shield structure has a function of reducing the reading blur of the magnetic field to be sensed. Is desirable. However, even if the gap between the upper and lower magnetic shields on both sides in the track width direction of the element is not made narrower than the reproducing gap 10, the gist of the present invention is not impaired.

  FIG. 4 shows the relationship between output and resistance in the giant magnetoresistive head according to the present invention, and magnetic domain control comprising a soft magnetic free layer / weakly antiparallel coupled layer / ferromagnetic antiparallel layer / single domained antiferromagnetic layer. 2 shows the output of a giant magnetoresistive head having a conventional structure (Patent Documents 1 and 2). Since the resistance of the single-domain antiferromagnetic layer is larger than the resistances of the other layers, the resistance of the entire magnetic head is increased in the conventional structure. The amount of change in resistance resulting from the change in the angle between the magnetization of the soft magnetic free layer and the magnetization of the ferromagnetic pinned layer is a constant value, so when the resistance of the entire head increases, the rate of change in resistance, that is, the output of the magnetic head decreases. End up. On the other hand, since the structure of the present invention does not use a single-domain antiferromagnetic layer having a large resistance, the resistance of the head is small, and a decrease in output as in the conventional structure is not observed.

  FIG. 5 shows a magnetic field response output curve in the giant magnetoresistive effect type magnetic head of the present invention and a magnetic field response output curve in the giant magnetoresistive effect type magnetic head of the conventional structure (Patent Document 3) by computer simulation. Here, the conventional structure has a magnetic domain control structure comprising a soft magnetic free layer / a weak antiparallel coupling layer / a ferromagnetic parallel layer / a strong antiparallel coupling layer / a ferromagnetic antiparallel layer. The magnetic field response output curve of the conventional structure responds with hysteresis to the signal magnetic field to be sensed. This is because, in the conventional structure, the magnetizations of the ferromagnetic parallel layer and the ferromagnetic antiparallel layer are not equal, so the magnetization of the two layers of the ferromagnetic antiparallel layer and the ferromagnetic parallel layer is sufficiently stable against the magnetic field. This is because an external magnetic field causes a deviation from a predetermined magnetization direction.

  FIG. 6 shows the magnetization state of the soft magnetic free layer in the conventional structure (Patent Document 3) obtained by computer simulation. As shown in FIG. 6, in the conventional structure, a deviation from a predetermined magnetization direction at the track end (especially, inside the broken line in the figure), that is, a remarkable angular difference appears in comparison with the magnetization direction in the center. . Therefore, as shown in FIG. 5, the output of the magnetoresistive element with respect to the magnetic field to be sensed becomes an unstable response curve having hysteresis.

  On the other hand, the magnetic field response output curve according to the structure of the present invention has a high linearity response with no hysteresis with respect to the signal magnetic field to be sensed. This is because the magnetizations of the ferromagnetic antiparallel layer and the ferromagnetic parallel layer are equal, so that the magnetization of the two layers realizes a local closed magnetic circuit and the magnetization does not fluctuate or change with respect to the signal magnetic field to be sensed. This is because the magnetization state is realized, and the ferromagnetic antiparallel layer is magnetically coupled to the soft magnetic free layer to make the soft magnetic free layer into a single magnetic domain.

  FIG. 7 shows the magnetization state of the soft magnetic free layer in the structure of the present invention obtained by computer simulation. As shown in FIG. 7, in the structure of the present invention, the magnetization of the soft magnetic free layer is directed in substantially the same direction over the entire surface, and the deviation of the magnetization direction at the track end is significantly larger than that in the prior art of FIG. It turns out that it has suppressed. The above results show that the structure of the present invention can realize a stable single domain state.

  In the structure of the present invention, as the first magnetic domain control layer and the second magnetic domain control layer, a Co alloy or FeCo alloy having a uniaxial magnetic anisotropic magnetic field or coercive force of 100 oersted (8 kA / m) or more is used. Thus, stable magnetic domain control can be realized, and more stable magnetic domain control can be realized as the uniaxial magnetic anisotropic magnetic field or coercive force is larger.

  FIG. 8 shows the result of computer simulation of the magnetic field response output curve when the uniaxial magnetic anisotropic magnetic field is changed in the structure of the present invention. As an example, FIG. 8 shows the results when the uniaxial magnetic anisotropic magnetic field is 100 oersted (8 kA / m) and 400 oersted (32 kA / m). As shown in FIG. 8, the linearity of the magnetic field response output curve improves as the uniaxial magnetic anisotropic magnetic field increases. This is because the larger the uniaxial magnetic anisotropy field or coercivity of the first magnetic domain control layer and the second magnetic domain control layer, the more stable the magnetization of the two layers does not change or change with respect to the signal magnetic field to be sensed. This is because it becomes a magnetized state. However, as shown in FIG. 8, the output decreases as the uniaxial magnetic anisotropic magnetic field increases. Therefore, the uniaxial magnetic anisotropic magnetic field is preferably 100 to 400 oersted (8 to 32 kA / m).

  The first magnetic domain control layer and the second magnetic domain control layer having a uniaxial magnetic anisotropic magnetic field or coercive force of 100 oersted (8 kA / m) or more can be realized by the following method, for example. (1) A method of adding an appropriate amount of materials such as Cr, Pt, Pd, Ta to Co alloy and FeCo alloy. (2) A method of forming a grazing incidence thin film during sputtering for forming a Co alloy or FeCo alloy. Alternatively, magnetic anisotropy due to the inverse magnetoelastic effect may be used.

  FIG. 9 is a diagram showing another configuration example of the present invention. The figure is a schematic view seen from the facing surface facing the magnetic medium. Adjacent to the weak antiparallel coupling layer 18, a single-domain ferromagnetic layer 35 composed of the first magnetic domain control layer 19 / second antiparallel coupling layer 20 / second magnetic domain control layer 21 is provided The anti-parallel coupling layer 20 is laminated n times (n is 2 or more).

  As an example, this figure shows a case where the single-domain ferromagnetic layer 35 is laminated twice. Also in this configuration, the film thickness and the material are selected so that the magnetization amounts of both the first magnetic domain control layer 19 and the second magnetic domain control layer 21 are equal as in the configuration shown in FIGS. . For example, although the case where the material which comprises the 1st magnetic domain control layer 19 and the 2nd magnetic domain control layer 21 is the same is the easiest embodiment, in this case, the film thickness of both is made equal. The second antiparallel coupling layer 20 generates a magnetic exchange coupling between the first magnetic domain control layer 19 and the second magnetic domain control layer 21 so that the first magnetic domain control layer 19 and the second magnetic domain control layer The control layer 21 generates a function of realizing an antiferromagnetic coupling state, that is, an antiparallel magnetization arrangement state. FIG. 10 shows a schematic diagram of the magnetization arrangement. Similar to the configuration shown in FIG. 1, in this configuration, the magnetization amount of the soft magnetic free layer 17 is M1, the magnetization amount of the first magnetic domain control layer 19 is M2, and the magnetization amount of the second magnetic domain control layer 21 is the same. When M3, M2≈M3, that is, M3−M2≈0.

  With such a configuration, the magnetizations of the first magnetic domain control layer 19 and the second magnetic domain control layer 21 are transferred via the second antiparallel coupling layer 20 based on the same principle as that shown in FIGS. Anti-ferromagnetic coupling and magnetostatic coupling due to the magnetic charges generated at the ends of the first magnetic domain control layer 19 and the second magnetic domain control layer 21 in the track width direction so as to be antiparallel to each other. Fix it. Further, the magnetization of the soft magnetic free layer 17 and the first magnetic domain control layer 19 closest to the soft magnetic free layer 17 is changed to an antiferromagnetic coupling via the first antiparallel coupling layer 18, and the soft magnetic free layer 17 Due to the magnetostatic coupling due to the magnetic charge generated at the end of the first magnetic domain control layer 19 closest to the soft magnetic free layer 17, the magnetic fields to be sensed are coupled so that they are in antiparallel directions when zero. As a result, the soft magnetic free layer can be stably made into a single magnetic domain.

  FIG. 11 is a conceptual diagram of a magnetic head equipped with the magnetoresistive effect element of the present invention. A magnetoresistive layered film 10, a lower magnetic shield 41, an upper magnetic shield 42, a lower magnetic core 61, a coil 63, and an upper magnetic pole core 62 are formed on a substrate 50 that also serves as a slider, and an opposing surface 81 is formed. Become. In the drawing, the structure includes an upper magnetic shield and a lower magnetic core. However, a structure using both the upper magnetic shield and the lower magnetic core does not impair the gist of the present invention. Similarly, in this figure, a current is passed in the film thickness direction through the upper magnetic shield and the lower magnetic shield that also serve as electrodes. However, other energization methods and energization directions do not impair the gist of the present invention. .

  FIG. 12 is a conceptual diagram when a magnetic head equipped with the magnetoresistive effect element of the present invention is used in a perpendicular magnetic recording apparatus. A lower magnetic shield 41, a magnetoresistive effect laminated film 10, an upper magnetic shield 42, a sub magnetic pole 66, a coil 63, and a main magnetic pole 65 are formed on a substrate 50 that also serves as a slider, and an opposing surface 81 is formed. In this figure, the upper magnetic shield and the auxiliary magnetic pole are provided. However, even if the upper magnetic shield and the auxiliary magnetic pole are combined, the gist of the present invention is not impaired.

  FIG. 13 shows a configuration example of a magnetic recording / reproducing apparatus using perpendicular magnetic recording in the present invention. A disk 91 holding a recording medium 95 for magnetically recording information is rotated by a spindle motor 93, and a head slider 90 is guided onto a track of the disk 91 by an actuator 92. That is, in the magnetic disk device, the reproducing head and the recording head formed on the head slider 90 move relative to a predetermined recording position on the disk 91 by this mechanism and sequentially write and read signals. is there. The actuator 92 is preferably a rotary actuator. The recording signal is recorded on the medium by the recording head through the signal processing system 94, and the output of the reproducing head is obtained as a signal through the signal processing system 94. Further, when the reproducing head is moved onto a desired recording track, the position on the track can be detected using a highly sensitive output from the reproducing head, and the actuator can be controlled to position the head slider. Although one head slider 90 and one disk 91 are shown in the figure, there may be a plurality of these. The disk 91 may have recording media 95 on both sides to record information. When information is recorded on both sides of the disc, the head slider 90 is arranged on both sides of the disc.

  As a result of testing the magnetic head of the present invention and the magnetic recording / reproducing apparatus equipped with the magnetic head of the present invention as described above, it showed sufficient output, good bias characteristics, and good operation reliability.

  The magnetic domain control structure using two ferromagnetic layers with the same amount of magnetization coupled antiferromagnetically according to the present invention includes a magnetic sensor using a perpendicular current type giant magnetoresistance effect called CPP-GMR, a magnetic head, and a tunnel. It can also be used for the magnetoresistive effect and the conventional magnetic sensor and magnetic head of CIP (in-plane current type) -GMR giant magnetoresistive effect.

1 is a diagram illustrating a configuration example of a magnetoresistive effect magnetic head of a vertical energization method according to the present invention. 1 is a diagram illustrating a configuration example of an in-plane energization type magnetoresistive magnetic head according to the present invention. The schematic diagram of a magnetization arrangement | sequence. FIG. 6 is a diagram illustrating an example of characteristics of a conventional technology and a magnetic head of the present invention. The figure which shows the magnetic field response output curve of the prior art and the magnetic head of this invention. The figure which shows the magnetization state of the soft-magnetic free layer in a conventional structure. The figure which shows the magnetization state of the soft-magnetic free layer of the magnetic head of this invention. FIG. 4 is a diagram showing an example of characteristics of the magnetic head of the present invention. FIG. 6 is a diagram showing another configuration example of the magnetoresistive effect type magnetic head of the present invention. The schematic diagram of a magnetization arrangement | sequence. 1 is a conceptual diagram of a magnetoresistive head of the present invention. 1 is a conceptual diagram of a magnetoresistive head of the present invention. The figure which shows the structural example of a magnetic recording / reproducing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Magnetoresistance effect laminated film 11 Underlayer film 12 Antiferromagnetic film 13 First ferromagnetic fixed layer 14 Antiparallel coupling film 15 Second ferromagnetic fixed layer 16 Nonmagnetic intermediate layer 17 Soft magnetic free layer 18 First antimagnetic layer Parallel coupling layer 19 First magnetic domain control layer 20 Second antiparallel coupling layer 21 Second magnetic domain control layer 22 Protective film 31 Ferromagnetic fixed layer 41 Lower magnetic shield 42 Upper magnetic shield 43 Lower electrode 44 Upper electrode 45 Electrode
DESCRIPTION OF SYMBOLS 50 Substrate 61 Lower magnetic pole core 62 Upper magnetic pole core 63 Coil 65 Main magnetic pole 66 Sub magnetic pole 71 Lower insulating layer 72 Upper insulating layer 81 Recording medium facing surface 90 Head slider 91 Disk 92 Actuator 93 Spindle motor 94 Signal processing circuit 95 Magnetic recording medium
M1 Magnetization of soft magnetic free layer
M2 Magnetization of the first magnetic domain control layer
M3 Magnetization of the second magnetic domain control layer
Magnetization of M4 ferromagnetic pinned layer

Claims (16)

A spin valve element in which a nonmagnetic intermediate layer is formed between a ferromagnetic pinned layer and a soft magnetic free layer;
A magnetic domain control structure formed on the soft magnetic free layer;
An electrode for applying a sense current to the spin valve element;
The magnetic domain control structure includes a first antiparallel coupling layer formed on the soft magnetic free layer, a first magnetic domain control layer formed on the first antiparallel coupling layer, and the first A second antiparallel coupling layer formed on one magnetic domain control layer, and a second magnetic domain control layer formed on the second antiparallel coupling layer,
The amount of magnetization of the first magnetic domain control layer and the amount of magnetization of the second magnetic domain control layer are substantially equal,
The first antiparallel coupling layer causes an antiferromagnetic coupling between the soft magnetic free layer and the first magnetic domain control layer to be substantially the same or weaker than the magnetic field to be sensed. ,
The second antiparallel coupling layer generates a sufficiently strong antiferromagnetic coupling between the first magnetic domain control layer and the second magnetic domain control layer with respect to a magnetic field to be sensed,
When the absolute value of the magnetization amount of the soft magnetic free layer is M1, the absolute value of the magnetization amount of the first magnetic domain control layer is M2, and the absolute value of the magnetization amount of the second magnetic domain control layer is M3, M1−M2 + M3 Magnetic head characterized by satisfying> 0. A spin valve element in which a nonmagnetic intermediate layer is formed between a ferromagnetic pinned layer and a soft magnetic free layer;
A magnetic domain control structure formed on the soft magnetic free layer;
An electrode for applying a sense current to the spin valve element;
The magnetic domain control structure includes a first antiparallel coupling layer formed on the soft magnetic free layer, a first magnetic domain control layer formed on the first antiparallel coupling layer, and the first A second antiparallel coupling layer formed on one magnetic domain control layer, and a second magnetic domain control layer formed on the second antiparallel coupling layer,
The first magnetic domain control layer and the second magnetic domain control layer have substantially the same film thickness,
The first antiparallel coupling layer includes an antiferromagnetic coupling having an exchange coupling magnetic field of 100 to 600 oersted (8 to 48 kA / m) between the soft magnetic free layer and the first magnetic domain control layer. Is what
The second antiparallel coupling layer is an antiferromagnetic layer having an exchange coupling magnetic field of 1 kilo-Oersted (80 kA / m) or more between the first magnetic domain control layer and the second magnetic domain control layer. That creates a bond,
When the absolute value of the magnetization amount of the soft magnetic free layer is M1, the absolute value of the magnetization amount of the first magnetic domain control layer is M2, and the absolute value of the magnetization amount of the second magnetic domain control layer is M3, M1−M2 + M3 Magnetic head characterized by satisfying> 0.   2. The magnetic head according to claim 1, wherein the first antiparallel coupling layer is formed of Ru, Ir, Cr, Rh, Re, Os, Pt, or an alloy thereof having a thickness of 0.2 to 1.0 nm, and a thickness of 0.3. A magnetic head comprising a laminate of 0.6 nm Cu, Au, Ag, Ta, Ti, or an alloy thereof.   3. The magnetic head according to claim 2, wherein the first antiparallel coupling layer is formed of Ru, Ir, Cr, Rh, Re, Os, Pt, or an alloy thereof having a thickness of 0.2 to 1.0 nm, and a thickness of 0.3. A magnetic head comprising a laminate of 0.6 nm Cu, Au, Ag, Ta, Ti, or an alloy thereof.   2. The magnetic head according to claim 1, wherein the second antiparallel coupling layer is made of Ru, Ir, Cr, Rh, Re, Os, Pt, or an alloy thereof having a thickness of 0.2 to 1.0 nm. Magnetic head.   3. The magnetic head according to claim 2, wherein the second antiparallel coupling layer is made of Ru, Ir, Cr, Rh, Re, Os, Pt, or an alloy thereof having a thickness of 0.2 to 1.0 nm. Magnetic head.   2. The magnetic head according to claim 1, wherein the electrode is disposed in a film thickness direction of the spin valve element.   3. The magnetic head according to claim 2, wherein the electrode is disposed in a film thickness direction of the spin valve element.   2. The magnetic head according to claim 1, wherein the electrode is disposed in an in-plane direction of the spin valve element.   3. The magnetic head according to claim 2, wherein the electrode is disposed in an in-plane direction of the spin valve element.   2. The magnetic head according to claim 1, wherein the first magnetic domain control layer and the second magnetic domain control layer are made of a Co alloy having a magnetic anisotropy or coercive force of 100 oersted (8 kA / m) or more, Fe-Co. A magnetic head comprising an alloy.   3. The magnetic head according to claim 2, wherein the first magnetic domain control layer and the second magnetic domain control layer are made of a Co alloy having magnetic anisotropy or coercive force of 100 oersted (8 kA / m) or more, Fe-Co. A magnetic head comprising an alloy.   2. The magnetic head according to claim 1, wherein magnetization directions of the first magnetic domain control layer and the second magnetic domain control layer are substantially fixed in a direction substantially orthogonal to a magnetic field to be sensed. And magnetic head.   3. The magnetic head according to claim 2, wherein the magnetization directions of the first magnetic domain control layer and the second magnetic domain control layer are substantially fixed in a direction substantially orthogonal to the magnetic field to be sensed. And magnetic head.   2. The magnetic head according to claim 1, wherein the soft magnetic free layer, the first magnetic domain control layer, and the second magnetic domain control layer have a magnetization state of the soft magnetic free layer in a state where a magnetic field to be sensed is near zero. A magnetic head, wherein the magnetization and the magnetization of the first magnetic domain control layer are antiparallel, and the magnetization of the first magnetic domain control layer and the magnetization of the second magnetic domain control layer are antiparallel. .   3. The magnetic head according to claim 2, wherein the soft magnetic free layer, the first magnetic domain control layer, and the second magnetic domain control layer have a magnetization state of the soft magnetic free layer when a magnetic field to be sensed is near zero. A magnetic head, wherein the magnetization and the magnetization of the first magnetic domain control layer are antiparallel, and the magnetization of the first magnetic domain control layer and the magnetization of the second magnetic domain control layer are antiparallel. .

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