JP2018133119A - Magnetic head, magnetic head assembly, and magnetic recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic head having a spin torque oscillator capable of oscillating at low current density.SOLUTION: The magnetic head comprises a main magnetic pole, a spin torque oscillator, and an auxiliary magnetic pole, the spin torque oscillator comprises a first magnetic layer including alloy of at least one element of Fe, Co, or Ni with one element of Cr, V, or Ti and consisting of an in-plane magnetization film having a negative spin-dependent scattering parameter, a non-magnetic intermediate layer, and a second magnetic layer including at least one element of Fe, Co, or Ni and consisting of an in-plane magnetization film having a positive spin-dependent scattering parameter.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a magnetic head, a magnetic head assembly, and a magnetic recording / reproducing apparatus.

  A conventional spin torque oscillator includes a spin injection layer and an oscillation layer, and a magnetic layer whose magnetization direction is fixed during operation is used for the spin injection layer. For example, a material having high anisotropy energy is used for the spin injection layer, and the spin torque oscillator has a separate spin injection layer in addition to the two-layer oscillation layer configuration in which the oscillation layer is composed of two magnetic layers. Is provided. When the oscillation layer is formed on the main magnetic pole side and the spin injection layer is formed on the auxiliary magnetic pole side with such a configuration, there is a problem that the current density necessary for oscillation increases due to processing damage of the spin injection layer.

JP 2008-277586 A

  An embodiment of the present invention aims to obtain a magnetic head that can be driven at a low current density.

According to an embodiment, a main pole,
An auxiliary magnetic pole provided opposite to the main magnetic pole;
A spin dependent scattering parameter that is provided between the main magnetic pole and the auxiliary magnetic pole and includes an alloy of at least one element of iron, cobalt, or nickel and one element of chromium, vanadium, or titanium; A first magnetic layer comprising an in-plane magnetization film, a nonmagnetic intermediate layer provided on the first magnetic layer, and at least one element of iron, cobalt, or nickel provided on the nonmagnetic intermediate layer Including a second magnetic layer made of an in-plane magnetization film having a positive spin-dependent scattering parameter,
There is provided a magnetic head comprising a spin torque oscillator having a negative sign of the magnetoresistance ratio of the giant magnetoresistance effect.

It is sectional drawing showing the structure of the magnetic head concerning embodiment. It is a graph showing the high frequency magnetic field intensity of a down track direction. It is a figure showing the structure of a comparative magnetic head. It is a figure showing an example of the composition of the magnetic recording and reproducing device concerning an embodiment. It is a figure showing an example of the composition of the magnetic head assembly concerning an embodiment.

The magnetic head according to the embodiment is
A main magnetic pole; an auxiliary magnetic pole provided opposite to the main magnetic pole; and a spin torque oscillator provided between the main magnetic pole and the auxiliary magnetic pole.

  The spin torque oscillator includes a first magnetic layer, a nonmagnetic intermediate layer provided on the first magnetic layer, and a second magnetic layer provided on the nonmagnetic intermediate layer, and includes a giant magnetoresistance effect (GMR) The sign of the magnetoresistance ratio is negative.

  The first magnetic layer is an in-plane magnetization film having a negative spin-dependent scattering parameter including an alloy of at least one element of iron, cobalt, or nickel and one element of chromium, vanadium, or titanium. .

  The second magnetic layer is an in-plane magnetization film having a positive spin-dependent scattering parameter and containing at least one element of iron, cobalt, or nickel.

  According to the embodiment, the current density necessary for oscillation can be reduced by configuring the spin torque oscillator with two in-plane magnetization films having different spin-dependent scattering parameters.

  In the magnetic head according to the embodiment, the demagnetizing field energy of the first magnetic layer is Ku1, the film thickness is t1, the demagnetizing field energy of the second magnetic layer is Ku2, and the film thickness is t2. The ratio (Ku2 × t2) / (Ku1 × t1) can satisfy the following relational expression (1).

0.3 ≦ (Ku2 × t2) / (Ku1 × t1) ≦ 1.2 (1)
When a spin torque oscillator having two magnetic layers satisfying Expression (1) is used, oscillation can be performed at a low current density.

  As a condition that the sign of the magnetoresistance ratio of the giant magnetoresistance effect (GMR) of the spin torque oscillator is negative, the spin-dependent scattering parameter of the material constituting the intermediate layer side of the first magnetic layer or the second magnetic layer is negative. The spin-dependent scattering parameter of the material constituting the intermediate layer side of the other magnetic layer is positive. On the other hand, if the GMR of the spin torque oscillator is positive, the spin-dependent scattering parameters of the constituent materials on the intermediate layer side of the first magnetic layer and the second magnetic layer are both negative or both positive.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 is a sectional view showing the configuration of the magnetic head according to the embodiment.

  A magnetic head 10 according to the embodiment is formed between a main magnetic pole 1 for applying a recording magnetic field, a trailing shield 2 facing the main magnetic pole 1 with a write gap, and the main magnetic pole 1 and the trailing shield 2. And a spin torque oscillator 8.

  The spin torque oscillator 8 includes an underlayer 3, a first magnetic layer 4, an intermediate layer 5, a second magnetic layer 6, and a cap layer 7.

  The underlayer 3 is formed for the purpose of preventing exchange coupling between the magnetization of the first magnetic layer and the magnetization of the main magnetic pole. Also, it is created to control the orientation of the first magnetic layer. As the underlayer 3, for example, a laminated film of an amorphous Ta layer and a nonmagnetic metal layer Cu, Cr, Ti or the like can be used. The total film thickness is desirably 1 nm or more. More preferably, it is 1-5 nm.

  The first magnetic layer 4 is made of a material having a characteristic that the spin-dependent scattering parameter is negative. Examples of the material having such characteristics include an alloy of at least one element of Fe, Co, or Ni and one element of Cr, V, and Ti. For example, FeCr alloy, FeV alloy, NiCr A ferromagnetic material containing an alloy can be used. Further, for example, it can be constituted by a single FeCr alloy or it can be constituted such that the FeCr alloy is on the intermediate layer side as a laminated film of FeCo alloy / FeCr alloy.

  As the intermediate layer 5, a nonmagnetic metal having a long spin diffusion length, such as Cu, Au, and Ag, can be used. Alternatively, Cr can be used. The thickness of the intermediate layer is preferably 0.5 nm or more and 5 nm or less. Alternatively, it can be made thicker and the upper limit can be set to about the spin diffusion length, for example, about 100 nm in the case of Cu.

  The second magnetic layer 6 is made of a material having a characteristic that the spin-dependent scattering parameter is positive. As a material having such characteristics, a material containing at least one element of Fe, Co, or Ni, such as an FeCo alloy, a Co-based Heusler alloy, and an FeCo / Ni artificial lattice, is used.

  The cap layer 7 is used to prevent the second magnetic layer 6 from being oxidized or etched when the spin torque oscillator 8 is processed. Examples of the material of the cap layer 7 include a single film such as Ta, Ru, and Cu, which are nonmagnetic metals, and a laminated film such as Ta / Ru and Ta / Cu / Ru.

  Next, the operation principle of the spin torque oscillator used in the embodiment will be described.

  As shown in FIG. 1, a strong gap magnetic field 9 is applied in the direction perpendicular to the film surface of the spin torque oscillator. Therefore, when not operating, the magnetizations of the first magnetic layer and the second magnetic layer are saturated in the direction perpendicular to the film surface. In operation, when a current is passed from the second magnetic layer in the direction 11 of the first magnetic layer, electrons whose spin direction is antiparallel to the gap magnetic field are transferred from the first magnetic layer to the second magnetic layer. Transmits and reflects from the second magnetic layer to the first magnetic layer. As a result, the second magnetic layer oscillates by receiving spin torque from the first magnetic layer, and the first magnetic layer oscillates by receiving spin torque from the second magnetic layer.

  Next, characteristics of the spin torque oscillator used in the embodiment will be shown.

  FIG. 2 is a graph showing the relationship between the down-track direction of the spin torque oscillator used in the embodiment and the generated high-frequency magnetic field strength.

  A graph 101 shows the high-frequency magnetic field strength generated from the first magnetic layer, and a graph 102 shows the high-frequency magnetic field strength generated from the second magnetic layer.

  As shown in the figure, the high-frequency magnetic field generated from each magnetic layer is considered to have the maximum intensity at the end face on the main pole side of each magnetic layer, and the spread (half-value width) is about the width of each magnetic layer. At the end face of the main magnetic pole, the high frequency magnetic field intensity from the second magnetic layer is attenuated, and the high frequency magnetic field intensity generated from the first magnetic layer is mostly. Therefore, it is considered that the high-frequency magnetic field generated from the first magnetic layer contributes to assist recording.

  Next, the magnetic characteristics of the first magnetic layer and the second magnetic layer will be described.

  The first magnetic layer and the second magnetic layer used in the embodiment are in-plane magnetization films. For this reason, the solid film is a material having a vertical saturation magnetic field substantially equal to the demagnetizing field 4πMs.

  The demagnetizing field energy Ku of each layer of the first magnetic layer and the second magnetic layer can be obtained from the following formulas (2) and (3).

Ku = MsHk / 2 (2)
Hk = (Nz−Nx, y) × 4πMs (3)
Here, Ms is saturation magnetization (emu / cc), Hk is a demagnetizing field (Oe), Nz is a demagnetizing field coefficient in the vertical direction when the element is processed, and Hx and y are demagnetizing fields in the in-plane direction when the element is processed. It is a coefficient.

Table 1 below shows saturation magnetization values and signs of spin-dependent scattering parameters for the magnetic materials used for the first magnetic layer and the second magnetic layer.

The material having a negative spin-dependent scattering parameter used for the first magnetic layer can be provided at least on the interface side of the intermediate layer. For example, a laminated structure such as Fe ₅₀ Co ₅₀ / Fe ₇₀ Cr ₃₀ can be used. When Cu, Ag, or Au is used for the intermediate layer, the film thickness of the Fe ₇₀ Cr ₃₀ alloy is 2.5 nm or more, the film thickness of the Fe ₉₀ Cr ₁₀ alloy is 8.5 nm or more, and the film thickness of the Fe ₈₅ V ₁₅ alloy. Can be made 6.0 nm or more. If the thickness is less than this, there is a tendency that the effect that the sign of the spin-dependent scattering parameter is negative cannot be obtained. When Cr is used for the intermediate layer, the film thickness can be set to 1 nm or more, and further, 1 nm to 5 nm. If it is 5 nm or more, spin information disappears in Cr. For the second magnetic layer, a material having a positive sign of the spin-dependent scattering parameter such as an Fe ₅₀ Co ₅₀ alloy is used. As described above, when materials having different signs of spin-dependent scattering parameters are used for the two magnetic layers, the critical current density of the spin torque oscillator is smaller than when materials having the same sign are used. Can be expected.

  The film thickness of the first magnetic layer can be such that the magnetic volume Ms1 × t1 (product of saturation magnetization Ms1 and film thickness t1) of the first magnetic layer is 15 to 30 nm T.

  The film thickness of the second magnetic layer can be configured such that the first magnetic layer and the second magnetic layer oscillate at the same threshold current density. The threshold current density is affected by (i) the spin injection efficiency from the other magnetic layer, and (ii) the magnetostatic interaction with the main magnetic pole (or auxiliary magnetic pole). The spin injection efficiency is highly related to the spin-dependent scattering parameter of the magnetic layer. For example, when the spin transfer efficiency from the first magnetic layer to the second magnetic layer is about 70% of the spin transfer efficiency from the second magnetic layer to the first magnetic layer, Ku2 × t2 (demagnetizing field) of the second magnetic layer. The product of the energy Ku2 and the film thickness t2 is preferably designed to be about 70% of Ku1 × t1 of the first magnetic layer. The spin injection efficiency of the first magnetic layer is between 30% and 120% of the spin injection efficiency of the second magnetic layer. Therefore, (Ku2 * t2) / (Ku1 * t1) is preferably between 0.3 and 1.2. If (Ku2 × t2) / (Ku1 × t1) is less than 0.3, the first magnetic layer does not oscillate, so the high-frequency magnetic field strength decreases. If (Ku2 × t2) / (Ku1 × t1) is greater than 1.2, the second magnetic layer does not oscillate, so that the distribution of the high-frequency magnetic field strength spreads.

According to the spin torque oscillator according to the embodiment, the first magnetic layer oscillates upon receiving the spin torque from the second magnetic layer. The second magnetic layer is made of a material having a good spin injection efficiency, such as Fe ₅₀ Co _50, and therefore, the first magnetic layer can oscillate at a low current density.

  The magnetic head assembly according to the embodiment is connected to the high-frequency assisted magnetic head shown in FIG. 1, a head slider on which the high-frequency assisted magnetic head is mounted, a suspension on which the head slider is mounted on one end, and the other end of the suspension. Actuator arm.

  The magnetic recording / reproducing apparatus according to the embodiment uses a magnetic head assembly having the high-frequency assisted magnetic head shown in FIG. 1 and writing and reading of signals to and from a magnetic recording medium using the high-frequency assisted magnetic head mounted on the magnetic head assembly. And a signal processing unit to perform.

  The direction of energization of the spin torque oscillator during recording on the magnetic recording medium is the direction in which current flows from the second magnetic layer 6 to the first magnetic layer 4 as indicated by an arrow 11.

  When the energization direction is a direction in which a current flows from the first magnetic layer 4 to the second magnetic layer 6, the operation does not work.

  FIG. 3 shows a configuration of a comparative magnetic head.

  The spin torque oscillator 28 is provided with a spin injection layer 26. The spin torque oscillator 28 is a multilayer film composed of an underlayer 23, an oscillation layer 24, an intermediate layer 25, a spin injection layer 26, and a cap layer 27. The underlayer 23 is a laminated structure of Ta and Cu, The oscillation layer 24 has a laminated structure of FeCoAl alloy, the intermediate layer 25 has Cu, the spin injection layer 26 has an FeCo / Ni artificial lattice, and the cap layer 27 has a laminated structure of Ta and Ru. The spin injection layer 26 has a large demagnetizing field energy Ku, and is designed so that its magnetization does not fluctuate during operation.

  As shown in FIG. 3, the gap magnetic field 19 is applied from the main magnetic pole 21 toward the auxiliary magnetic pole 22 in a direction perpendicular to the film surface of the main magnetic pole 21, as represented by an arrow 31. The magnetizations of 24 and the spin injection layer 26 are substantially parallel to the gap magnetic field. In this state, when a current is passed from the spin injection layer 26 to the oscillation layer 24 in the direction of the arrow 31, the oscillation layer receives the spin torque from the spin injection layer and oscillates. At this time, since the magnetization of the spin injection layer 26 does not fluctuate, a high frequency magnetic field is generated from the oscillation layer.

  The magnetic energy Ku of the spin injection layer 26 is one digit or more larger than the magnetic energy Ku of the spin injection layer 6 of the magnetic head according to the embodiment, for example, about 5 Merg / cc. The film thickness of the spin injection layer 26 is about 8 nm, for example.

  FIG. 4 shows an example of the magnetic head assembly according to the embodiment, and shows an enlarged perspective view of the magnetic head assembly ahead of the actuator arm as viewed from the disk side.

  As shown in the figure, the magnetic head assembly 160 has an actuator arm 155 having a bobbin portion for holding a drive coil, for example, and a suspension 154 is connected to one end of the actuator arm 155.

  A head slider 103 on which the magnetic head 10 shown in FIG. 1 is mounted is attached to the tip of the suspension 154. The suspension 154 has a lead wire 164 for writing and reading signals, and the lead wire 164 and each electrode of the magnetic head incorporated in the head slider 103 are electrically connected. In the figure, reference numeral 162 denotes an electrode pad of the magnetic head assembly 160.

  FIG. 5 is a perspective view of a principal part illustrating a schematic configuration of a magnetic recording / reproducing apparatus in which the magnetic head and the magnetic head assembly according to the embodiment can be mounted.

  The magnetic recording / reproducing apparatus 150 according to the embodiment is an apparatus using a rotary actuator. The recording medium disk 180 is mounted on the spindle 153 and is rotated in the direction of arrow A by a motor (not shown) that responds to a control signal from a drive device control unit (not shown). The magnetic recording / reproducing apparatus 150 may include a plurality of medium disks 180.

  A head slider 103 that records and reproduces information stored in the medium disk 180 is attached to the tip of a thin film suspension 154 in the magnetic head assembly 160. Here, the head slider 103 has, for example, the magnetic head according to the embodiment mounted near its tip.

  When the medium disk 180 rotates, the medium facing surface (ABS) of the head slider 103 is held with a predetermined flying height from the surface of the medium disk 180. Alternatively, a so-called “contact traveling type” in which the slider contacts the medium disk 180 may be used.

  The suspension 154 is connected to one end of an actuator arm 155 having a bobbin portion for holding a drive coil (not shown). A voice coil motor 156, which is a kind of linear motor, is provided at the other end of the actuator arm 155. The voice coil motor 156 is composed of a drive coil (not shown) wound around the bobbin portion of the actuator arm 155, and a magnetic circuit composed of a permanent magnet and a counter yoke arranged so as to sandwich the coil.

  The actuator arm 155 is held by ball bearings (not shown) provided at two positions above and below the spindle 157, and can be freely rotated and slid by a voice coil motor 156.

  Examples will be described below, and the embodiment will be described more specifically.

  Example

  First, layers having the following materials and thicknesses were sequentially laminated on the main magnetic pole made of FeCo alloy by using a DC magnetron sputtering method.

Underlayer Ta 2nm / Cu 2nm
First magnetic layer Fe ₅₀ Co ₅₀ 7.4 nm / Fe ₇₀ Cr ₃₀ 2.6 nm
Intermediate layer Cu 2nm
Second magnetic layer Fe ₅₀ Co ₅₀ 6 nm
Cap layer Ru 10nm
The first magnetic layer had a magnetic volume Ms1 × t1 of 20 nm T and a film thickness t1 of 10 nm. The average amount of magnetization is 1590 emu / cc, and the demagnetizing field energy Ku1 of the first magnetic layer is about 10 Merg / cc.

  The second magnetic layer was designed such that the magnetic anisotropy energy volume Ku2 × t2 was 70% of the magnetic anisotropy energy volume Ku1 × t1. The amount of magnetization is 1800 emu / cc, and the demagnetizing field energy Ku2 of the second magnetic layer is about 19 Merg / cc.

  A mask layer for defining the size of the spin torque oscillator in the stripe height direction was formed on the cap layer. Thereafter, the base layer of the spin torque oscillator was etched through the mask layer by IBE (ion beam etching) until the main pole was exposed. An insulating film SiOx was formed on the periphery of the element, and then the mask layer was removed. A spin torque oscillator was formed on the main pole by forming a mask layer on the cap layer for defining the size in the track width direction and processing the same.

  Next, an auxiliary magnetic pole made of a NiFe alloy was formed on the cap layer of the obtained spin torque oscillator to produce a magnetic head having the same configuration as that shown in FIG.

When the current density required for oscillation of this magnetic head was examined, it was 0.5 × 10 ⁸ A / cm ² .

  Similar to Example 1, except that layers having the following materials and thicknesses are sequentially stacked on the main pole similar to Example 1 to form a spin torque oscillator by using DC magnetron sputtering. Thus, a magnetic head was produced.

Underlayer Ta 2nm / Cu 2nm
First magnetic layer Fe ₅₀ Co ₅₀ 5.5 nm / Fe ₉₀ Cr ₁₀ 10 nm
Intermediate layer Cu 2nm
Second magnetic layer Fe ₅₀ Co ₅₀ 2.2 nm
Cap layer Ru 10nm
The first magnetic layer had a magnetic volume Ms1 × t1 of 30 nmT and a film thickness t1 of 15.5 nm. The average amount of magnetization is 1540 emu / cc, and the demagnetizing field energy Ku1 of the first magnetic layer is 7.6 Merg / cc.

  The second magnetic layer was designed so that the magnetic anisotropy energy volume Ku2 × t2 was 40% of the magnetic anisotropy energy volume Ku1 × t1. The amount of magnetization is 1800 emu / cc, and the demagnetizing field energy Ku2 of the second magnetic layer is about 20 Merg / cc.

When the current density necessary for oscillation of this magnetic head was examined, it was 1.5 × 10 ⁸ A / cm ² .

  Similar to Example 1, except that layers having the following materials and thicknesses are sequentially stacked on the main pole similar to Example 1 to form a spin torque oscillator by using DC magnetron sputtering. Thus, a magnetic head was produced.

Underlayer Ta 2nm / Cu 2nm
First magnetic layer Fe ₅₀ Co ₅₀ 7.4 nm / Fe ₇₀ Cr ₃₀ 2.6 nm
Intermediate layer Cr 1nm / Cu 1nm
Second magnetic layer Fe ₅₀ Co ₅₀ 3 nm
Cap layer Ru 10nm
The first magnetic layer had a magnetic volume Ms1 × t1 of 20 nm T and a film thickness t1 of 10 nm. The average amount of magnetization is 1590 emu / cc, and the demagnetizing field energy Ku1 of the first magnetic layer is about 10 Merg / cc.

  The second magnetic layer was designed so that the magnetic anisotropy energy volume Ku2 × t2 was 60% of the magnetic anisotropy energy volume Ku1 × t1. The amount of magnetization is 1800 emu / cc, and the demagnetizing field energy Ku2 of the second magnetic layer is about 20 Merg / cc.

When the current density required for oscillation of this magnetic head was examined, it was 0.5 × 10 ⁸ A / cm ² .

  Similar to Example 1, except that layers having the following materials and thicknesses are sequentially stacked on the main pole similar to Example 1 to form a spin torque oscillator by using DC magnetron sputtering. Thus, a magnetic head was produced.

Underlayer Ta 2nm / Cu 2nm
First magnetic layer Fe ₅₀ Co ₅₀ 5 nm / Fe ₈₅ V ₁₅ 6 nm
Intermediate layer Cr 1nm / Cu 1nm
Second magnetic layer Fe ₅₀ Co ₅₀ 2 nm
Cap layer Ru 10nm
The first magnetic layer had a magnetic volume Ms1 × t1 of 20 nm T and a film thickness t1 of 11 nm. The average amount of magnetization is 1490 emu / cc, and the demagnetizing field energy Ku1 of the first magnetic layer is about 9 Merg / cc.

  The second magnetic layer was designed such that the magnetic anisotropy energy volume Ku2 × t2 was 30% of the magnetic anisotropy energy volume Ku1 × t1. The amount of magnetization is 1800 emu / cc, and the demagnetizing field energy Ku2 of the second magnetic layer is about 20 Merg / cc.

  As in the following embodiment, the first magnetic layer may be on the auxiliary magnetic pole side and the second magnetic layer may be on the main magnetic pole side.

When the current density required for oscillation of this magnetic head was examined, it was 0.5 × 10 ⁸ A / cm ² .

  Similar to Example 1, except that layers having the following materials and thicknesses are sequentially stacked on the main pole similar to Example 1 to form a spin torque oscillator by using DC magnetron sputtering. Thus, a magnetic head was produced.

Underlayer Ta 2nm / Cu 2nm
Second magnetic layer Fe ₅₀ Co ₅₀ 13.3 nm
Intermediate layer Cu 2nm
First magnetic layer Fe ₇₀ Cr ₃₀ 2.6 nm / Fe ₅₀ Co ₅₀ 7.4 nm
Cap layer Ru 6nm
The second magnetic layer had a magnetic volume Ms2 × t2 of 30 nmT and a film thickness t2 of 13.3 nm. The demagnetizing field energy Ku1 of the first magnetic layer is about 10 Merg / cc. The magnetization amount of the second magnetic layer is 1800 emu / cc, and the demagnetizing field energy Ku2 is about 9 Merg / cc.

  The second magnetic layer was designed so that the magnetic anisotropy energy volume Ku2 × t2 was 2/3 times the magnetic anisotropy energy volume Ku1 × t1 of the first magnetic layer.

When the current density necessary for oscillation of this magnetic head was examined, it was 1.5 × 10 ⁸ A / cm ² .

Comparative Example 1

  As Comparative Example 1 of Examples 1, 3, and 4, the same structure as that shown in FIG. 3 except that layers having the following materials and thicknesses are sequentially laminated on the main pole by using the DC magnetron sputtering method. A magnetic head having

  The magnetic volume Ms × t of the oscillation layer of this configuration was set to 20 nm T, which is the same as the magnetic volume Ms1 × t1 of the first nonmagnetic layer of Examples 1, 3, and 4.

Underlayer Ta 2nm / Cu 2nm
Oscillation layer Fe ₅₀ Co ₅₀ 8.8 nm
Intermediate layer Cu 2nm
Spin injection layer FeCo / Ni artificial lattice 8nm
Cap layer Ru 10nm
Regarding the high-frequency magnetic field strength, Examples 1, 3, and 4 and Comparative Example 1 are substantially equal. The current density required for oscillation was examined and compared. As a result, in Examples 1, 3, and 4, 0.5 × 10 ⁸ A / cm ² , and in Comparative Example 1, 0.8 × 10 ⁸ A / cm 2. ² .

Comparative Example 2

  As Comparative Example 2 of Examples 2 and 5, a magnetic head was produced in the same manner except that layers having the following materials and thicknesses were sequentially laminated on the main pole using the DC magnetron sputtering method.

  The magnetic volume Ms × t of the oscillation layer of this configuration was set to 30 nmT, which is the same as the magnetic volume Ms1 × t1 of the first nonmagnetic layer of Example 2. Moreover, it was set to 30 nmT which is the same as the magnetic volume Ms2 × t2 of the second nonmagnetic layer of Example 5.

Underlayer Ta 2nm / Cu 2nm
Oscillation layer Fe ₅₀ Co ₅₀ 13.2 nm
Intermediate layer Cu 2nm
Spin injection layer FeCo / Ni artificial lattice 8nm
Cap layer Ru 10nm
And it processed by the same process and formed the auxiliary magnetic pole.

As for the high-frequency magnetic field strength, Examples 2 and 5 and Comparative Example 2 are substantially equal. The current density required for oscillation was examined and compared. As a result, in Examples 2 and 5, no oscillation was observed in 1.5 × 10 ⁸ A / cm ² and in Comparative Example 2.

  As described above, the current density required for oscillation can be reduced by forming the two magnetic films with the in-plane magnetization film. As a result, a larger high-frequency magnetic field can be generated.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1,21 ... Main magnetic pole, 2,21 ... Auxiliary magnetic pole, 3 ... Underlayer, 4 ... First magnetic layer, 5, 25 ... Intermediate layer, 6 ... Second magnetic layer, 7, 27 ... Cap layer, 8, 28 ... spin torque oscillation layer, 9, 19 ... gap time, 10, 20 ... magnetic head, 11, 31 ... current direction, 24 ... oscillation layer, 26 ... spin injection layer

Claims (4)

The main pole,
An auxiliary magnetic pole provided opposite to the main magnetic pole;
A spin dependent scattering parameter that is provided between the main magnetic pole and the auxiliary magnetic pole and includes an alloy of at least one element of iron, cobalt, or nickel and one element of chromium, vanadium, or titanium; A first magnetic layer comprising an in-plane magnetization film, a nonmagnetic intermediate layer provided on the first magnetic layer, and at least one element of iron, cobalt, or nickel provided on the nonmagnetic intermediate layer Including a second magnetic layer made of an in-plane magnetization film having a positive spin-dependent scattering parameter,
A magnetic head comprising: a spin torque oscillator having a negative sign of the magnetoresistance ratio of the giant magnetoresistance effect. The demagnetizing field energy of the first magnetic layer is Ku1, the film thickness is t1,
When the demagnetizing field energy of the second magnetic layer is Ku2, and the film thickness is t2,
The magnetic head according to claim 1, wherein the following relational expression (1) is satisfied.
0.3 ≦ (Ku2 × t2) / (Ku1 × t1) ≦ 1.2 (1) A magnetic head according to claim 1 or 2,
A head slider on which the magnetic head is mounted;
A suspension for mounting the head slider at one end;
A magnetic head assembly comprising: an actuator arm connected to the other end of the suspension.   3. A magnetic head comprising the magnetic head according to claim 1 and a magnetic recording medium, wherein an energization direction to the spin torque oscillator during recording on the magnetic recording medium is from the second magnetic layer to the first magnetic layer A magnetic recording / reproducing apparatus characterized in that the current flows in a direction in which the current flows.

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