JP2007142322A - Magnetism detection element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetism detection element capable of increasing a magnetism resistance change rate (ΔR/R) and lowering coupling cohesion magnetism (Hin) affecting a free magnetic layer. <P>SOLUTION: A fixed magnetic layer 3, a non-magnetic material layer 2, and the free magnetic layer 1 are sequentially laminated from the bottom, an oxide layer 16 constituted of CoFeCr that is oxidized is formed on the layer 1, and a tantalum oxide layer 19 is formed on the layer 16. This allows, a specular effect to be properly exerted and the coupling cohesion magnetism (Hin) affecting the layer 1 to be properly lowered while a high resistance change rate (ΔR/R) is maintained, thereby enabling the system to obtain stable reproduction characteristics. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic detecting element for reproduction mounted on a hard disk device or the like, and in particular, to increase a magnetoresistance change rate (ΔR / R) and reduce a coupling coupling magnetic field (Hin) exerted on a free magnetic layer. The present invention relates to a magnetic detection element that can be used.

  Patent Document 1 shown below discloses a magnetic detecting element for reproduction. In Patent Document 1, a CoFe oxide constituting a free magnetic layer (free layer) is formed in an oxidation process in the manufacturing process of the magnetic sensing element, and the CoFe oxide functions as a specular reflection layer. It is described.

  It is disclosed that the mean free path of conduction electrons is increased by the presence of the specular reflection layer, and the magnetoresistance change rate (ΔR / R) can be increased.

  Further, in Patent Document 1, a protective layer formed of Ta oxide or the like is formed on the reflective layer so as to be in contact with the reflective layer (specular layer) formed on the magnetic detection element. Are listed.

  The point of providing a Ta oxide layer as a protective layer of the magnetoresistive effect element is also described in the following Patent Document 2 ([0091] column of Patent Document 2).

Further, the reflective layer (specular layer) can also be provided, for example, in the free magnetic layer as described in FIG. In the [0312] column of Patent Document 3, “the specular film 94 is formed by, for example, forming the magnetic material layer 93 and oxidizing the surface of the magnetic material layer 93. The oxide layer functions as the specular film 94. Then, a magnetic material layer 95 is formed on the specular film 94. " In addition, the material of the specular layer is disclosed in the [0313] column of Patent Document 3.
JP 2002-076474 A JP 2003-188440 A JP 2003-298139 A

  However, in the configuration in which the Ta oxide layer is formed on the CoFe oxide layer as in the magnetic detection element described in Patent Document 1, according to the experiment described later, the resistance change rate (ΔR / R) And the coupling coupling magnetic field (Hin) exerted on the free magnetic layer could not be reduced.

  It was found that when the Ta oxide layer was formed with a very thick film thickness, the specular effect was reduced because the film was not completely oxidized, and the resistance change rate (ΔR / R) was lowered. Therefore, it is desired to form the Ta oxide layer thinly, but if the film thickness in the vicinity where the rate of change in resistance (ΔR / R) is maximized is selected, the coupling magnetic field (Hin) tends to increase, and the resistance change The coupling coupling magnetic field (Hin) increases rapidly only by slightly reducing the thickness of the Ta oxide layer from the thickness in the vicinity of the highest rate (ΔR / R), and thus the coupling coupling magnetic field. In order to reduce (Hin) with certainty, the Ta oxide layer had to be formed with a slightly thick film, and as a result, the resistance change rate (ΔR / R) had to be sacrificed.

  Although it is preferable to reduce the coupling magnetic field (Hin) in order to suppress an increase in asymmetry and obtain stability of reproduction characteristics, conventionally, a high resistance change rate (ΔR / R) is obtained and the coupling is performed. The coupling magnetic field (Hin) could not be reduced.

  Although Patent Document 2 and Patent Document 3 disclose an oxide Ta layer as a specular layer and an oxide layer formed by oxidizing a magnetic material, the specular effect is effective except that a specular layer is provided. A structure for enhancing the speed is not disclosed. In particular, the coupling coupling magnetic field (Hin) is not mentioned at all.

  Accordingly, the present invention solves the above-described conventional problems, and can increase the magnetoresistance change rate (ΔR / R) and reduce the coupling coupling magnetic field (Hin) exerted on the free magnetic layer. An object is to provide an element.

In the present invention, a pinned magnetic layer, a nonmagnetic material layer, and a free magnetic layer are laminated in this order from the bottom
An oxide layer formed by oxidizing CoFeCr is formed on the free magnetic layer,
A Ta oxide layer is formed on the oxide layer.

  As described above, the specular effect is appropriately exhibited, and the coupling coupling magnetic field (Hin) exerted on the free magnetic layer can be appropriately reduced while maintaining a high rate of change in resistance (ΔR / R), thereby obtaining stable reproduction characteristics. It is possible.

  In the present invention, the thickness of the Ta oxide layer is preferably in the range of 16 to 24 mm. In the case where an oxide layer formed by oxidizing CoFe is formed on the free magnetic layer as in the prior art, if the Ta oxide layer is thinned to the above extent, the rate of change in resistance (ΔR) is within the above film thickness range. / R) and coupling coupling magnetic field (Hin) values are very large, and when the film thickness is reduced within the above range, the rate of change in resistance (ΔR / R) rapidly decreases and the coupling coupling magnetic field ( It is known from experiments to be described later that Hin) rises rapidly. This is presumably because the free magnetic layer / CoFe oxide layer / Ta oxide layer has a laminated structure, and if the Ta oxide layer is thinly formed, the free magnetic layer is easily oxidized. On the other hand, in the present invention, it is considered that the oxidation of the free magnetic layer can be suppressed even if the Ta oxide layer is formed as thin as described above in a laminated structure of a free magnetic layer / CoFeCr oxide layer / Ta oxide layer. Thus, the variation of the resistance change rate (ΔR / R) and the coupling coupling magnetic field (Hin) within the above film thickness range can be reduced as compared with the conventional case. The resistance change rate (ΔR / R) can take the maximum value within the film thickness range, and the resistance change rate (ΔR / R) decreases even when the film thickness decreases within the film thickness range. On the other hand, the coupling coupling magnetic field (Hin) increases slightly as the film thickness decreases within the above-mentioned film thickness range, but it is proved by experiments described later that the increase is very moderate. Therefore, in the present invention, by controlling the film thickness of the Ta oxide layer within the above range, the coupling coupling magnetic field can be maintained while maintaining a high resistance change rate (ΔR / R) as compared with the prior art. (Hin) can be appropriately reduced.

  Moreover, in this invention, it is preferable that the film thickness of the said oxide layer exists in the range of 4-8cm. If the CoFeCr oxide layer is formed with a very thick film thickness, the magnetostriction of the free magnetic layer increases, and if formed with a very thin film thickness, the rate of change in resistance (ΔR / R) decreases. It is known from experiments. Therefore, in the present invention, by limiting the thickness of the oxide layer within the above range, the magnetostriction of the free magnetic layer can be reduced, and the resistance change rate (ΔR / R) can be stably increased. .

  In the present invention, a pinned magnetic layer, a nonmagnetic material layer, and a free magnetic layer are stacked in this order from the bottom, an oxide layer formed by oxidizing CoFeCr is formed on the free magnetic layer, and an oxide Ta layer is formed on the oxide layer. A layer is formed.

  As described above, the specular effect is appropriately exhibited, and the coupling coupling magnetic field (Hin) exerted on the free magnetic layer can be appropriately reduced while maintaining a high rate of change in resistance (ΔR / R), thereby obtaining stable reproduction characteristics. It becomes possible.

  FIG. 1 is a cross-sectional view of the entire structure of the present embodiment as viewed from the side facing the recording medium. In FIG. 1, only the central portion of the element extending in the X1-X2 direction is shown broken away. The magnetic detection element A1 shown in FIG. 1 is a so-called spin valve magnetoresistive effect element, and is provided at the trailing side end of a floating slider provided in a hard disk device, so that a recording magnetic field of a hard disk or the like is generated. It is to detect. The moving direction of a magnetic recording medium such as a hard disk is the Z direction in the figure, and the direction of the leakage magnetic field from the magnetic recording medium is the Y direction.

  The lowermost layer in FIG. 1 is an underlayer 6 formed of a nonmagnetic material such as one or more elements of Ta, Hf, Nb, Zr, Ti, Mo, and W. The foundation layer 6 may not be formed.

  A seed layer 22 is formed on the underlayer 6. By forming the seed layer 22, the crystal grain size in the direction parallel to the film surface of each layer formed on the seed layer 22 can be increased. It is possible to more appropriately improve the magnetoresistance change rate (ΔR / R).

The seed layer 22 is formed of NiFeCr alloy, Cr, or the like.
The antiferromagnetic layer 4 formed on the seed layer 22 includes an element X (where X is one or more of Pt, Pd, Ir, Rh, Ru, and Os) and Mn. It is preferable to form with the antiferromagnetic material containing these.

  X-Mn alloys using these platinum group elements have excellent properties as antiferromagnetic materials, such as excellent corrosion resistance, a high blocking temperature, and a large exchange coupling magnetic field (Hex). In particular, it is preferable to use Pt or Ir among platinum group elements. For example, a PtMn alloy or an IrMn alloy formed in a binary system can be used.

  In the present invention, the antiferromagnetic layer 4 includes the element X and the element X ′ (where the element X ′ is Ne, Ar, Kr, Xe, Be, B, C, N, Mg, Al, Si, P, 1 of Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, Cd, Sn, Hf, Ta, W, Re, Au, Pb, and rare earth elements It may be formed of an antiferromagnetic material containing Mn and a seed or two or more elements.

  The pinned magnetic layer 3 formed on the antiferromagnetic layer 4 includes a first magnetic layer 13 in contact with the interface 4a with the antiferromagnetic layer 4 and a nonmagnetic layer on the first magnetic layer 13. A laminated ferrimagnetic structure is constituted by the second magnetic layer 11 formed through the intermediate layer 12.

  A nonmagnetic material layer 2 is formed on the pinned magnetic layer 3. The nonmagnetic material layer 2 is made of Cu, for example.

  Further, a free magnetic layer 1 is formed on the nonmagnetic material layer 2. In the embodiment shown in FIG. 1, the free magnetic layer 1 is formed of a two-layer structure of a first layer 14 and a second layer 15 formed on the first layer 14. The first layer 14 can be formed of a magnetic material such as CoFe, and the second layer 1b can be formed of a magnetic material such as NiFe. Further, the first layer 14 can function as an enhancement layer. The enhancement layer is preferably formed of a magnetic material having a higher spin polarizability than the first layer 14. CoFe has a higher spin polarizability than NiFe. The enhancement layer may be provided separately from the first layer 14 and the second layer 15. In such a case, it is preferable that the enhancement layer has a higher spin polarizability than the first layer 14 and the second layer 15. By forming the enhancement layer, the rate of change in resistance (ΔR / R) can be improved more effectively. The free magnetic layer 1 may be formed with a single layer structure, or may be formed with a laminated ferrimagnetic structure like the pinned magnetic layer 3.

  An oxide layer 16 formed by oxidizing CoFeCr is formed on the free magnetic layer 1. The oxide layer 16 has a function as a specular reflection layer (specular layer) for increasing the mean free path of conduction electrons contributing to the magnetoresistance change. The oxide layer 16 is formed by natural oxidation of CoFeCr or by oxidation using a method other than natural oxidation such as plasma oxidation or radical oxidation.

  In the embodiment shown in FIG. 1, a Ta oxide layer 19 is formed on the oxide layer 16. The Ta oxide layer 19 is a protective layer, but also contributes to the improvement of the specular effect.

  In the magnetic detection element A1 shown in FIG. 1, the hard bias layers 5 and 5 and the electrode layers 8 and 8 are provided on both sides in the track width direction (X1-X2 direction in the drawing) of the laminate from the base layer 6 to the Ta oxide layer 19. Is formed.

  The hard bias layers 5 and 5 are made of, for example, a Co—Pt (cobalt-platinum) alloy or a Co—Cr—Pt (cobalt-chromium-platinum) alloy, and the electrode layers 8 and 8 are made of α-Ta. , Au, Ru, Rh, Cr, Cu (copper), W (tungsten) and the like.

  In the magnetic detection element A1 shown in FIG. 1, the magnetization of the pinned magnetic layer 3 is parallel to the height direction by the exchange coupling magnetic field generated between the antiferromagnetic layer 4 (the direction parallel to the Y2 direction in the drawing). It is fixed to. For example, the magnetization of the first magnetic layer 13 is fixed in the Y2 direction, and the second magnetic layer 11 is fixed in the direction opposite to the Y2 direction.

  On the other hand, the free magnetic layer 1 is weak enough to rotate and rotate with respect to the external magnetic field in the right direction (X2 direction in the figure) in the track width direction by the longitudinal bias magnetic field supplied from the hard bias layers 5 and 5. It is in the state of becoming.

  The electric resistance flowing between the electrode layers 8 and 8 changes depending on the relationship between the fixed magnetization direction of the fixed magnetic layer 3 and the magnetization direction of the free magnetic layer 1 affected by the external magnetic field. The external signal from the recording medium is reproduced by the voltage change based thereon. The magnetic detection element 1 shown in FIG. 1 is a CIP-GMR type magnetic detection element in which a sense current flows in the horizontal direction with respect to the film surface of the free magnetic layer 1.

  A characteristic part of the magnetic detection element shown in FIG. 1 will be described. As described above, the oxide layer 16 formed by oxidizing CoFeCr is formed on the free magnetic layer 1, and the oxidized Ta layer 19 is formed on the oxide layer 16. In the present embodiment, by providing the CoFeCr oxide layer 16 on the free magnetic layer 1, the free magnetic layer 1 can be prevented from being oxidized even if the Ta oxide layer 19 is thinly formed. The resistance change rate (ΔR / R) can be maintained, and the coupling coupling magnetic field (Hin) exerted on the free magnetic layer 1 can be reduced.

  The thickness of the Ta oxide layer 19 is preferably in the range of 16 to 24 mm. According to the experiment described later, when the film thickness of the Ta oxide layer 19 is adjusted within the above range, the maximum value of the resistance change rate (ΔR / R) can be obtained, and the cup at the film thickness is obtained. The ring coupling magnetic field (Hin) can be kept small. Further, when the thickness of the Ta oxide layer 19 is reduced within the above-mentioned thickness range, the rate of change in resistance (ΔR / R) gradually decreases, but the decrease is caused by using an oxide of CoFe. On the other hand, the coupling coupling magnetic field (Hin) gradually increases, but the increase is more gradual than the conventional one using CoFe oxide. If the thickness of the Ta oxide layer 19 is adjusted, it is possible to manufacture a magnetic sensing element that can satisfy both a high resistance change rate (ΔR / R) and a small coupling magnetic field (Hin). Since the coupling coupling magnetic field (Hin) can be reduced, an increase in asymmetry can be suppressed and the stability of the reproduction characteristics can be achieved. When used in an actual magnetic head, an upper gap layer made of alumina or the like is formed on the Ta oxide layer 19, but the specular interface does not change due to mutual diffusion between the Ta oxide layer and alumina. Thus, it is preferable to provide a diffusion preventing layer between the Ta oxide layer 19 and the upper gap layer. The diffusion preventing layer is, for example, a Ta oxide layer. In such a case, it is preferable that the total thickness of the Ta oxide layer 19 and the oxidized Ta layer as the diffusion preventing layer thereon is about 60 to 80 mm.

  Next, the thickness of the oxide layer 16 is preferably in the range of 4 to 8 mm. According to the experiment described later, when the thickness of the oxide layer 16 is less than 4 mm, the rate of change in resistance (ΔR / R) decreases, and when the thickness of the oxide layer 16 is greater than 8 mm, free magnetic properties are obtained. It has been found that the magnetostriction of layer 1 is increased. The CoFeCr oxide layer 16 has a higher ability to suppress oxidation of the free magnetic layer 1 than the CoFe oxide layer, but if it is too thin, the ability is weakened and the free magnetic layer 1 is easily oxidized. As a result, it is considered that the rate of change in resistance (ΔR / R) decreases. On the other hand, even if the film thickness of the oxide layer 16 is too thick, the CoFeCr is not completely oxidized and partially remains as CoFeCr, which is originally compared with NiFe and CoFe (material of the free magnetic layer 1). Therefore, it is considered that the magnetostriction of the free magnetic layer 1 is increased by being dragged by CoFeCr having a large magnetostriction. Therefore, by setting the thickness of the oxide layer 16 within the range of 4 to 8 mm, the rate of change in resistance (ΔR / R) can be stably increased and the magnetostriction of the free magnetic layer 1 can be decreased. . Since the magnetostriction of the free magnetic layer 1 can be reduced, the sensitivity of the free magnetic layer 1 to an external magnetic field can be improved, and the stability of reproduction output can be improved.

  The composition ratio of CoFeCr will be described. Co is adjusted in a range of 40 to 87 at%, Fe in a range of 10 to 60 at%, and Cr in a range of 3 to 20 at%, and a value obtained by adding the composition ratio of these three elements is adjusted to 100 at%.

  Note that there may be element diffusion between layers due to heat treatment or the like. Therefore, an oxide high concentration region where the CoFeCr oxide concentration is higher than other regions exists on the free magnetic layer, and the Ta oxide concentration is higher than that of the other regions above the oxide high concentration region. A form in which a high concentration region of high oxidized Ta exists is also possible.

  The composition analysis is performed by nano-beam characteristic X-ray analysis (Nano-beam EDX) using a SIMS analyzer or an electrolytic emission transmission electron microscope (FE-TEM).

A method of manufacturing the magnetic detection element in the present embodiment will be described. First, the base layer 6, the seed layer 22, the antiferromagnetic layer 4, the pinned magnetic layer 3, the nonmagnetic material layer 2, and the free magnetic layer 1 are stacked and formed on the free magnetic layer 1 by sputtering or the like. A CoFeCr alloy layer is formed by sputtering or the like. At this time, the CoFeCr alloy layer is formed in a thickness of 2 to 4 mm. Then, the CoFeCr alloy layer is oxidized to form an oxide layer 16. As the oxidation method, an existing oxidation method such as natural oxidation, plasma oxidation, or radical oxidation can be used. In the case of natural oxidation, the oxidation strength is preferably 10 ML to 1 GL (about 1.33 × 10 ^{3 to} 1.33 × 10 ⁵ (Pa · s)). The entire CoFeCr alloy layer formed with a thickness of 2 to 4 mm can be appropriately oxidized. As a result, an oxide layer 16 formed by oxidizing CoFeCr is formed on the free magnetic layer 1. The film thickness of the oxide layer 16 is in the range of 4 to 8 mm.

  Next, Ta is sputter-deposited on the oxide layer 16 with a predetermined thickness, and the Ta layer is oxidized by the above method to form an oxidized Ta layer 19. In the present embodiment, the Ta layer is preferably formed with a thickness of 8 to 12 mm. For example, although the Ta layer is naturally oxidized, the Ta layer as a whole can be appropriately oxidized when the film thickness is this level. The film thickness of the oxidized Ta layer 19 formed by oxidizing the Ta layer is in the range of 16 to 24 mm.

  After processing the laminated body from the underlayer 6 to the Ta oxide layer 19 in the form shown in FIG. 1, the hard bias layers 5 and 5 and the electrode layers 8 are formed on both sides of the track width (X1-X2 direction) of the laminated body. 8 is laminated. The pinned magnetic layer 3 receives an exchange coupling magnetic field generated between the pinned magnetic layer 3 and the antiferromagnetic layer 4 and is pinned in a direction parallel to the height direction (direction parallel to the Y2 direction in the drawing). On the other hand, the free magnetic layer 1 is supplied with a bias magnetic field from the hard bias layers 5 and 5 and is magnetized in a track width direction (a direction parallel to the X1-X2 direction 9 in the drawing).

  Moreover, in this embodiment, you may perform a surface modification process in arbitrary locations. In the surface modification treatment, pure Ar gas is introduced into a vacuum chamber, and low-energy plasma is generated on an arbitrary layer surface to the extent that sputtering does not occur. Thereby, the surface roughness of the layer surface is reduced.

  Immediately after the plasma treatment, a small amount of oxygen is introduced into the vacuum chamber in addition to pure Ar gas. Then, since the layer surface is activated by the plasma treatment described above, oxygen is adsorbed on the layer surface in a mixed gas atmosphere of pure Ar gas and oxygen, for example. Oxygen adsorbed on the surface of the layer functions as a surfactant. Thereby, the interface flatness and crystallinity of each layer laminated on the layer surface can be improved, and the resistance change rate (ΔR / R) can be improved and the coupling coupling magnetic field (Hin) can be reduced. It can be promoted more effectively.

  The interface modification treatment is performed, for example, on the surface of the nonmagnetic intermediate layer 12 and the surface of the second magnetic layer 11 shown in FIG.

  The magnetic detection element shown in FIG. 1 was formed. In the magnetic detection element shown in FIG. 1, the laminated part at the center of the element was formed with the following film configuration.

Substrate / seed layer: {Ni _0.8 Fe _0.2 } _{60 at%} Cr _{40 at%} (42 Å) / antiferromagnetic layer: IrMn (55 Å) / pinned magnetic layer [Co _{70 at%} Fe _{30 at%} (12 Å) / Ru ( 8.7 Å) / Co (22 Å)] / Nonmagnetic material layer: Cu (19 Å) / Free magnetic layer: [Co _{90 at%} Fe _{10 at%} (12 Å) / Co _{70 at%} Fe _{30 at%} / Ni _{80 at%} Fe _{20 at%} ( 13.5 Å)] / {Fe _0.55 Co _0.45 } _{95 at%} Cr _{5 at%} (2.5 Å) / Ta. The numerical value in the parenthesis indicates the film thickness.

After depositing {Fe _0.55 Co _0.45 } _{95 at%} Cr _{5 at%} on the free magnetic layer, the film was oxidized at an oxidation strength of 100 ML (about 1.33 × 10 ⁴ (Pa · s)). The Ta layer was naturally oxidized. That is, the Ta layer becomes an oxidized Ta layer after natural oxidation.

  In the experiment, the thickness of the Ta layer was changed, and the relationship between the thickness of the Ta layer and the rate of resistance change (ΔR / R) was examined.

As a comparative example, based on the above film structure, a {Fe _0.55 Co _0.45 } _{95 at%} Cr _{5 at%} portion is formed of 3 _% CoFe, and CoFe is 1 ML (about 1.33 × 10 ² (Pa S)) is oxidized at the oxidation strength, and a magnetic sensing element is formed on which the Ta layer (which is an oxidized Ta layer by natural oxidation) is formed, and the thickness of the Ta layer is increased. The relationship between the film thickness at the time of forming the Ta layer and the rate of change in resistance (ΔR / R) was examined. The experimental results are shown in FIG. In addition to the film thickness at the time of film formation of the Ta layer, the film thickness of the oxidized Ta layer is also shown on the horizontal axis in FIG.

  As shown in FIG. 2, it was found that the rate of change in resistance (ΔR / R) can be increased by forming the CoFeCr oxide layer on the free magnetic layer as compared to the case of forming the CoFe oxide layer. . When the CoFeCr oxide layer is formed, as shown in FIG. 2, when the thickness of the Ta layer is within a range of 8 to 12 mm (the thickness of the oxidized Ta layer is 16 to 24 mm), the resistance is within that range. The maximum value of the rate of change (ΔR / R) can be obtained, and even if the resistance change rate (ΔR / R) is formed thinner than the maximum thickness, the rate of change of resistance (ΔR / R) It can be seen that can be increased compared to the case of using a CoFe oxide layer. As shown in FIG. 2, in the case of using a CoFe oxide layer, the rate of change in resistance (ΔR / R) suddenly decreases when the film thickness of the Ta layer becomes smaller than 12 mm. In the case of using a physical layer, it was found that the rate of change in resistance (ΔR / R) was gradual, and a high rate of change in resistance (ΔR / R) could still be obtained.

  Next, the relationship between the film thickness at the time of forming the Ta layer and the coupling magnetic field (Hin) exerted on the free magnetic layer was examined using the magnetic detection element used in the experiment of FIG. The experimental results are shown in FIG. The horizontal axis of FIG. 3 shows the thickness of the Ta oxide layer in addition to the thickness of the Ta layer.

  As shown in FIG. 3, using either the CoFeCr oxide layer or the CoFe oxide layer, if the film thickness of the Ta layer is increased (if the film thickness of the Ta oxide layer is increased), Although the coupling coupling magnetic field (Hin) can be reduced, it has been found that the coupling coupling magnetic field (Hin) can be slightly reduced by using the CoFeCr oxide layer.

  As shown in FIG. 3, when the film thickness of the Ta layer is decreased (when the film thickness of the Ta oxide layer is decreased), the magnitude of the coupling coupling magnetic field (Hin) is increased by the CoFeCr oxide. A remarkable difference was observed between the case where the layer was used and the case where the CoFe oxide layer was used.

  As shown in FIG. 3, it was found that when the CoFe oxide layer was used, the coupling coupling magnetic field (Hin) increased rapidly when the film thickness of the Ta layer was set to 12 mm or less. This is presumably because the free magnetic layer is affected by oxidation. On the other hand, when a CoFeCr oxide layer is used, even if the film thickness of the Ta layer is set to 12 mm or less, the coupling magnetic field (Hin) tends to increase gradually as the film thickness is reduced. However, the increase of the coupling coupling magnetic field (Hin) was slow, and it was found that the coupling coupling magnetic field (Hin) can be reduced more appropriately than in the case of using a CoFe oxide layer.

  When the CoFeCr oxide layer is used, when the film thickness of the Ta layer is in the range of 8 to 12 mm (the film thickness of the oxidized Ta layer is 16 to 24 mm), the CoFe oxide layer is used. In comparison, it was found that the coupling coupling magnetic field (Hin) can be reduced while maintaining a high rate of change in resistance (ΔR / R).

  Next, in the magnetic detection element shown in FIG. 1, the laminated part at the center of the element was formed with the following film configuration.

Substrate / seed layer: {Ni _0.8 Fe _0.2 } _{60 at%} Cr _{40 at%} (42 Å) / antiferromagnetic layer: IrMn (55 Å) / pinned magnetic layer [Co _{70 at%} Fe _{30 at%} (12 Å) / Ru ( 8.7 Å) / Co (22 Å)] / Nonmagnetic material layer: Cu (19 Å) / Free magnetic layer: [Co _{90 at%} Fe _{10 at%} (12 Å) / Co _{70 at%} Fe _{30 at%} / Ni _{80 at%} Fe _{20 at%} ( 13.5 Å)] / {Fe _0.55 Co _0.45 } _{95 at%} Cr _{5 at%} / Ta (16 Å). The numerical value in the parenthesis indicates the film thickness.

After depositing {Fe _0.55 Co _0.45 } _{95 at%} Cr _{5 at%} on the free magnetic layer, the film was oxidized at an oxidation strength of 100 ML (about 1.33 × 10 ⁴ (Pa · s)). The Ta layer was naturally oxidized. That is, the Ta layer becomes an oxidized Ta layer after natural oxidation.

  In the experiment, the thickness of the CoFeCr alloy layer was changed, and the relationship between the thickness of the CoFeCr alloy layer and the rate of change in resistance (ΔR / R) was examined. The experimental results are shown in FIG. The horizontal axis of FIG. 4 shows the thickness of the CoFeCr oxide layer in addition to the thickness of the CoFeCr alloy layer. As shown in FIG. 4, it was found that the rate of change in resistance (ΔR / R) decreases as the film thickness of the CoFeCr alloy layer decreases (when the film thickness of the oxide layer decreases).

  FIG. 5 shows the results of examining the relationship between the thickness of the CoFeCr alloy layer and the magnetostriction of the free magnetic layer, using the sample used in the experiment of FIG. The horizontal axis of FIG. 5 also shows the thickness of the CoFeCr oxide layer in addition to the thickness of the CoFeCr alloy layer.

  As shown in FIG. 5, it was found that the magnetostriction of the free magnetic layer increases as the thickness of the CoFeCr alloy layer increases (when the thickness of the oxide layer increases). The magnetostriction of the free magnetic layer should be as small as possible. The film thickness of the CoFeCr alloy layer can be reduced to 2 to 4 mm (of the CoFeCr oxide layer) in order to ensure the resistance change rate (ΔR / R) stably at a high value and reduce the magnetostriction of the free magnetic layer. It has been found that it is preferable to set the film thickness to 4 to 8 cm. When the film thickness of the CoFeCr alloy layer is set to 3 to 4 mm (the film thickness of the CoFeCr oxide layer is 6 mm to 8 mm), a high resistance change rate (ΔR / R) can be secured stably and free It was found that the magnetostriction of the magnetic layer can be stably reduced.

Sectional drawing which looked at the whole structure of the magnetic detection element of this embodiment from the opposing surface side with a recording medium, For the magnetic sensing element shown in FIG. 1 using a CoFeCr oxide layer and the magnetic sensing element in which the oxide layer is replaced with a CoFe oxide layer, the film thickness and resistance change of the Ta layer (Ta oxide layer) A graph showing the relationship with the rate (ΔR / R), The magnetic sensing element shown in FIG. 1 using a CoFeCr oxide layer and the magnetic sensing element in which the oxide layer is replaced with a CoFe oxide layer, the thickness of the Ta layer (Ta oxide layer) and the coupling A graph showing the relationship with the coupling magnetic field (Hin); FIG. 1 is a graph showing the relationship between the thickness of a CoFeCr alloy layer (CoFeCr oxide layer) and the rate of change in resistance (ΔR / R) for the magnetic sensing element shown in FIG. FIG. 1 is a graph showing the relationship between the thickness of the CoFeCr alloy layer (CoFeCr oxide layer) and the magnetostriction of the free magnetic layer for the magnetic sensing element shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Free magnetic layer 2 Nonmagnetic material layer 3 Fixed magnetic layer 4 Antiferromagnetic layer 5 Bias layer 8 Electrode layer 11 Second magnetic layer 12 Nonmagnetic intermediate layer 13 First magnetic layer 16 CoFeCr oxide layer 19 Ta oxide layer

Claims (3)

The pinned magnetic layer, nonmagnetic material layer, and free magnetic layer are stacked in this order from the bottom.
An oxide layer formed by oxidizing CoFeCr is formed on the free magnetic layer,
A magnetic sensing element, wherein a Ta oxide layer is formed on the oxide layer.   The magnetic sensing element according to claim 1, wherein the thickness of the Ta oxide layer is in a range of 16 to 24 mm.   The magnetic sensing element according to claim 1, wherein the oxide layer has a thickness in a range of 4 to 8 mm.

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