JP2005285242A - Magnetic recording head and magnetic storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel magnetic recording head and a magnetic storage device which realize energy irradiation by a heat assist method and contribute to reduction of a write current magnetic field of MRAM.
A recording magnetic pole, a magnetization free layer formed in the vicinity of the recording magnetic pole, a nonmagnetic layer laminated on the magnetization free layer, and a magnetization laminated on the nonmagnetic layer are formed. And a pair of electrodes 391 and 393 that can be energized in a direction perpendicular to the film surfaces of the magnetization free layer 31, the nonmagnetic layer 35, and the magnetization fixed layer 35. A magnetic recording head comprising: a spin wave oscillator that excites a spin wave in the magnetization free layer 31 by a spin polarized current injected from the layer 35 into the magnetization free layer 31.
[Selection] Figure 2

Description

  The present invention relates to a magnetic recording device such as a magnetic recording head and a magnetic random access memory.

Since the advent of GMR heads that use the giant magnetoresistive effect (GMR effect) as a read magnetic head, the recording density of magnetic recording has improved at an annual rate of 100%. The GMR element consists of a laminated film with a sandwich structure of ferromagnetic layer / nonmagnetic layer / ferromagnetic layer, exhibits a magnetoresistance effect of about 10%, and can handle recording densities of about 200 Gbit / inch ² (Gbpsi). It is considered to be deaf.

  Development of a TMR element using the tunnel magnetoresistive effect (TMR effect) is underway in order to support higher density magnetic recording. The TMR element is composed of a laminated film of a ferromagnetic layer / insulator / ferromagnetic layer, and an MR ratio of about 50% is obtained at the maximum, and it is considered that it can cope with a recording density of about 300 Gbpsi.

  On the other hand, in magnetic recording of several hundred Gbpsi or more, the bit size is about several tens of nm to 100 nm, so that the coercive force of the magnetic medium becomes extremely large in order to reduce the thermal fluctuation of micro magnetization. For this reason, it is considered that a heat assist method for simultaneously supplying a magnetic field and heat is necessary during magnetic recording. In the heat assist method, heat irradiation with a large power density having both high-speed recording and locality is required, and a laser heat assist method has been proposed (Non-Patent Document 1).

In addition, it has been pointed out that in a magnetic random access memory (MRAM) using the recording magnetization of a magnetic material as storage information, an increase in current magnetic field for writing due to high integration is pointed out.
T. Rausch, Jpn.J.Appl.Phys. 42 (2003) pp.989-994

  As described above, in high-density magnetic recording, a method of simply irradiating energy in the heat assist method is required. In addition, reduction of write current is also an issue in MRAM.

  In view of such circumstances, the present invention has an object to provide a novel magnetic recording head and a magnetic storage device that realize energy irradiation by a thermal assist method and contribute to the reduction of the write current magnetic field of the MRAM. To do.

  In view of the above problems, the first of the present invention is a recording magnetic pole, a magnetization free layer formed in the vicinity of the recording magnetic pole, a non-magnetic layer laminated on the magnetization free layer, and a non-magnetic layer. Magnetized from the magnetization fixed layer by energization, comprising a laminated magnetization fixed layer with fixed magnetization, and a pair of electrodes that can be energized in a direction perpendicular to the film surfaces of the magnetization free layer, nonmagnetic layer, and magnetization fixed layer Provided is a magnetic recording head comprising a spin wave oscillator for exciting a spin wave in a magnetization free layer by a spin polarized current injected into the free layer.

  The second aspect of the present invention is a recording magnetic pole, a magnetization free layer formed in the vicinity of the recording magnetic pole, a non-magnetic layer laminated on the magnetization free layer, and a non-magnetic layer. A magnetization fixed layer and a pair of electrodes that can be energized in a direction perpendicular to the film surfaces of the magnetization free layer, the nonmagnetic layer, and the magnetization fixed layer, and injecting a spin fluctuation current from the magnetization free layer into the magnetization fixed layer And a magnetic recording head comprising a spin wave oscillator for inducing magnetic resonance or a spin wave in a magnetization fixed layer.

  A third aspect of the present invention is a magnetic tunnel junction element in which a plurality of magnetic layers are laminated via a dielectric layer, and magnetic information can be stored by reversal of at least one magnetization of the plurality of magnetic layers, and a magnetic tunnel junction element A magnetization free layer in which the magnetization fluctuates, a nonmagnetic layer stacked on the magnetization free layer, a magnetization fixed layer with fixed magnetization stacked on the nonmagnetic layer, a magnetization free layer, a nonmagnetic layer A pair of electrodes that can be energized in a direction perpendicular to the film surface of the magnetization fixed layer and the magnetization fixed layer, and spin waves are excited in the magnetization free layer by a spin-polarized current injected from the magnetization fixed layer to the magnetization free layer by energization There is provided a magnetic storage device comprising a spin wave oscillator.

  According to a fourth aspect of the present invention, a magnetic tunnel junction element capable of storing magnetic information by reversing at least one magnetization of a plurality of magnetic layers and a recording magnetic pole are stacked. Magnetization free layer formed and magnetization is fluctuated, nonmagnetic layer laminated on magnetization free layer, magnetization fixed layer laminated on nonmagnetic layer, magnetization free layer, nonmagnetic layer, and magnetization fixed layer A pair of electrodes that can be energized in a direction perpendicular to the plane, and injecting a spin fluctuation current from the magnetization free layer into the magnetization fixed layer by energization, and applying the spin fluctuation current from the magnetization free layer by the energization And a spin wave oscillator capable of inducing magnetic resonance or spin waves in the magnetization fixed layer.

  According to the present invention, it is possible to provide a novel magnetic recording head and magnetic storage device that realizes energy irradiation by the heat assist method and contributes to reduction of the write current magnetic field of the MRAM.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol shall be attached | subjected to a common structure through embodiment and an Example, and the overlapping description is abbreviate | omitted. Each figure is a schematic diagram for promoting explanation and understanding of the invention, and its shape, dimensions, ratio, etc. may be different from the actual device, but these are considered in the following explanation and known technology. The design can be changed as appropriate.

(First embodiment)
A first embodiment relating to a magnetic recording head of the present invention will be described with reference to FIGS. 1A and 1B and FIGS. 2 to 6, taking a perpendicular magnetic recording head as an example.

  FIGS. 1A and 1B are perspective views showing the relationship between a magnetic recording track and a magnetic recording / reproducing head. The magnetic recording track 1 is a part of the magnetic recording medium, and only an arbitrary magnetic recording track 1 is displayed in FIG. 1A for convenience of illustration. If the magnetic recording medium is disk-shaped, it is rotated around its central axis, and the medium and the magnetic head move relative to each other (in FIG. 1A, the magnetic head advances in the direction of arrow A).

  Perpendicular magnetizations 1a and 1b are recorded on the magnetic recording track 1 by a magnetic recording head. The magnetic recording head includes a recording magnetic pole 5 extending rearward from the medium facing surface and an electromagnetic coil (not shown) that imparts desired magnetization to the recording magnetic pole 5. A spin wave oscillator 3 for heating the magnetic recording track 1 is provided in front of the recording magnetic pole 5 on the medium facing surface side. The spin wave oscillator 3 locally heats the magnetic recording track 1 prior to recording by the recording magnetic pole 5.

  A magnetic read head is provided on the rear side of the recording magnetic pole 5 on the medium facing surface side. The read head includes a sense element 7 such as a magnetoresistive effect element and the front and rear of the element 7 moving the head. A pair of shields 9a and 9b sandwiched between the lead wires (not shown) for supplying a sense current to the sense element 7 and the like.

  The spin wave oscillator 3 is classified into a spin torque type and a spin resonance type because of the difference in the structure of the oscillation layer.

  The spin torque type includes two magnetic layers, a magnetization free layer in which magnetization fluctuates and a magnetization fixed layer in which magnetization does not substantially fluctuate. The oscillation element excites spin waves in the magnetization free layer by a spin-polarized current injected from the magnetization fixed layer (first magnetic layer 31) to the magnetization free layer (second magnetic layer 33).

  In the spin resonance type, a spin fluctuation current is injected into the second magnetic layer 33 from a magnetization free layer (first magnetic layer 31) of a micro magnetic material whose magnetization fluctuates, and magnetic resonance or spin waves are injected into the second magnetic layer 33. Is an oscillating element that induces.

  As a means for fixing the magnetization of the magnetization fixed layer, there are a method of using an antiferromagnetic layer on the magnetic layer and utilizing exchange coupling between them, a method of using a high coercive force material for the magnetic layer, and the like. . On the other hand, a material having a coercive force such that magnetization is rotated by an applied magnetic field is used for the magnetization free layer.

  Although the spin wave excitation principle is different, each spin wave oscillator needs to include at least two magnetic bodies. The element structure and operation common to the two spin torque type and spin resonance type oscillation elements will be described below.

  The spin wave oscillator 3 will be described with reference to the perspective views of FIGS.

  The spin wave oscillator 3 includes a laminated film including a first magnetic layer 31, a second magnetic layer 33, and a nonmagnetic layer 35 formed therebetween. A strong spin wave is excited in the second magnetic layer 33 by passing a current through the laminated film perpendicularly to the surface of each layer. Therefore, the spin wave oscillator 3 includes a pair of electrodes 391 and 393 for applying this current.

  The spin wave oscillator 3 includes a hard bias film 371 formed in contact with the first magnetic layer 31 or via a metal such as Ta. The hard bias film 371 is for applying a bias magnetic field to the second magnetic layer 33 that oscillates a spin wave, and for increasing the heating efficiency by being close to the magnetic resonance frequency of the medium by controlling the oscillation frequency. .

  2 and 3, a metal such as Ta for ensuring flatness is formed between the electrode 391 and the second magnetic layer 33 to protect the electrode, but this layer is not essential. . The arrows in the hard bias film 371, the first magnetic layer 31, and the second magnetic layer 33 in the figure indicate the magnetization directions of the respective layers. In FIG. 2, the magnetization of each layer is in the in-plane direction of the layer, and in FIG. 3, each magnetization is in the film thickness direction of the layer.

  In order to heat the medium by the high-frequency oscillating magnetic field generated from the spin wave oscillator 3, it is effective that the azimuth direction of the oscillating magnetic field has a component orthogonal to the magnetization direction of the medium. That is, the magnetization fluctuation direction of the magnetic layer excited by the spin wave becomes a magnetic field by a magnetic dipole that vibrates in the z-axis direction, and this magnetic field needs to have a component orthogonal to the medium magnetization direction.

  When the second magnetic layer 33 has in-plane magnetization as shown in FIG. 2, the high-frequency magnetic field generated by the element is generated by a magnetic dipole that vibrates in the Z-axis direction in a plane parallel to the YZ plane. To do. Therefore, in the element of the oscillation layer having in-plane magnetization, the XY plane, YZ plane, or XZ plane can be the medium facing surface. The structure of FIG. 2 shows the case where the XZ plane is the medium facing surface and the Z-axis direction is the head moving direction. Since the YZ surface on which the electrode surface is formed is disadvantageous for adjusting the distance from the medium, the XZ surface or the XY surface should be the medium facing surface.

  The track width and bit width are determined by the recording bit size of the medium (see the schematic top view of FIG. 4A and the recording bit perspective view of FIG. 4B). If the size is about the same as that, the heat recording can be performed efficiently. The bit width and track width in the figure show the optimum element size when the XY plane is the medium facing surface.

  On the other hand, when the second magnetic layer 33 is perpendicularly magnetized as shown in the perspective view of FIG. 3, a magnetic field is generated by a magnetic dipole that vibrates in a plane parallel to the XY plane and the YZ plane. The medium facing surface becomes a surface. The bit width and track width shown in FIG. 3 indicate the optimum element size when the XY plane is the medium facing surface. In FIG. 3, the moving direction of the recording head is the X-axis direction.

With such a spin wave oscillator 3, the magnitude of the microwave magnetic field acting on the minute recording portion (corresponding to the bit recording portion) of the magnetic recording track 1 immediately below is about h = 10 ³ to 10 ⁴ Oe. Here, the distance between the spin wave oscillator 3 and the magnetic recording medium surface was about 10 nm, and the volume and magnetization of the oscillation layer (second magnetic layer) 33 were about 30 × ³⁰ × 10 nm ³ and about 10 ³ Gauss, respectively.

  The microwave power P absorbed by the magnetic recording medium depends on the imaginary part χ ″ of the magnetic susceptibility of the medium, and is expressed as in equation (1).

χ ″ (ω) strongly depends on the frequency, and is small and less than 1 at a frequency away from the resonance frequency of the medium, but increases to about 10 to 100 at or near the resonance frequency of the medium. The heating efficiency of the medium is absorbed. It is important to heat at a frequency close to the resonance frequency of the medium because it depends on the power P. When the oscillator frequency is close to the resonance frequency of the medium, the power absorbed by the medium is expressed by the following equation (1). It is estimated that 10 ¹⁸ to 10 ²¹ erg / s cm ³ per unit volume, provided that ω is 2πx (10 ¹⁰ to 10 ¹¹ ) / s assuming a resonance frequency of 10 to 100 GHz.

As an example, consider the case where FePt having a heat capacity of about 3 × 10 ⁷ erg / Kcm ³ is used for the magnetic medium. The minute portion of the medium is locally heated by the spin wave oscillator 3, and the anisotropic energy _Ku1 of the minute portion is reduced. In order to perform recording under an external magnetic field of several KOe applied by the recording magnetic pole, it is necessary to raise the temperature of the minute portion by about 100 K (° C.) from room temperature. That is, when the writing speed is 1 GHz, a temperature increase rate of about 100 K / ns is required.

On the other hand, since it takes about 1 ns for the recording magnetic pole 5 to reach above the minute part heated by the spin wave oscillator, the minute part due to heat conduction or radiation is not required in order that the heated part does not cool during that time. The heat dissipation rate must be 100K / ns or less. Using the heat capacity, this heat release rate corresponds to an energy release rate of ³ × 10 ¹⁸ erg / s cm ³ .

FIG. 5 is a schematic diagram showing the relationship between the power (10 ¹⁸ to 10 ²¹ erg / s cm ³ ) supplied from the spin wave oscillator 3 to a minute portion of the medium and the energy release rate (3 × 10 ¹⁸ erg / s cm ³ or less). FIG. If the oscillation frequency is adjusted to increase χ ″ (ω) and the difference between the supply power and the emission power becomes 3 × 10 ¹⁸ erg / s cm ³ or more, the temperature rising rate can be made 100 K / ns or more. The wave oscillator makes it possible to increase the temperature of the minute part of the medium by 100 K (° C) or more within 1 ns.

  The oscillation frequency f of the spin torque oscillator 3 is expressed as shown in Expression (2) when the oscillation layer 33 is a ferromagnetic material.

Here, γ is the magnetic rotation ratio, H is the bias magnetic field from the hard bias film 371, H _K = 2K _u1 / Ms is the anisotropic magnetic field of the oscillation layer (second magnetic layer 33), and _{Ku 1} is the difference of the oscillation layer. The isotropic energy, Ms, is the saturation magnetization of the oscillation layer. Bias field H is at most several 100 Oe, 4 [pi] Ms is of the order of 10 ⁴ Oe, anisotropy field H _K can be varied in a wide range of 10~5x10 ⁴ Oe by selecting appropriate material.

That oscillation frequency f of the spin-wave oscillator 3 from equation (2) can be varied in a wide range of several 10GHz several 100MHz by varying the anisotropy field H _K of the oscillation layer 33.

In the case of the FePt medium described above, since the resonance frequency is about 50 GHz, the frequency of the spin wave oscillator 3 is preferably about 50 GHz. For this purpose, H _K (10 ⁴ Oe (K _u1 (10 ⁷ erg / cm ³ ) Must be used as the oscillation layer 33.

Since the resonance frequency of a magnetic film used as a high-density recording medium, not limited to FePt, is 10 GHz or more, it is desirable that Ku _{1 of the} oscillation layer 33 is 5 × 10 ⁶ erg / cm ³ or more. Examples of such magnetic films include alloys containing about 50 atomic percent or more of CoCr such as CoCrTa, CoCrTaPt, CoCrTaNb, Co multilayer films such as Co layer / Pd layer, Co layer / Pt layer, CoCrTa layer / Pd layer, etc. CoCrPt alloys, FePt alloys, SmCo alloys containing rare earths, TbFeCo alloys, and the like can be considered.

  Further, since the ferromagnetic / antiferromagnetic laminated film using the exchange bias also exhibits a large anisotropic magnetic field (in this case, not uniaxial but unidirectional), this laminated film is used as the oscillation layer 33. It is also possible. Here, FeMn, NiMn, FeNiMn, FeMnRh, RhMn, CoMn, CrMn, CrMnPt, CrMnPt, CrMnRh, CrMnCu, CrMnPd, CrMnIr, CrMnNi, CrMnCo, CrMnTi, PtMn, PdMn, IrMn, etc. are used as antiferromagnetic materials. can do.

  On the other hand, in the spin resonance type oscillator, the artificial anti-strength in which a Co layer / Ru layer, a Co layer / Pd layer, a Fe layer / Cr layer, etc., which are laminated with a ferromagnetic layer and a nonmagnetic layer, are repeatedly laminated as the oscillation layer 33. A magnetic material is used. The oscillation frequency in this case is expressed as shown in Equation (3).

Here H _E exchange magnetic field of the ferromagnetic layers, the H _A is the anisotropy field. In this case, H _A is at most but is about 1000 Oe H _E rapidly increases when the film thickness depends on the thickness of the nonmagnetic layer decreases. Therefore, in order for the oscillation frequency of Equation (3) to be 10 GHz or more, it is desirable that the thickness of the nonmagnetic material layer in the artificial antiferromagnetic material is about 1 nm or less.

  The material of the ferromagnetic layer in the artificial antiferromagnet is Fe, Co, Ni and an alloy containing at least one of them. The material of the nonmagnetic layer is Pt, Au, Ag, Cu, Cr, Ru, Pd, Rh, Re, Os, Mo, W, and an alloy containing at least one of them.

  The thickness of the ferromagnetic layer in the artificial antiferromagnet is 0.1 nm or more and 2 nm or less, more preferably 1 nm or less. The thickness of the non-magnetic layer is preferably 0.5 or more and 2 nm or less, more preferably 1 nm or less.

  Writing by the recording head of the present embodiment will be described with reference to the energy diagram of FIG. FIG. 6A is an energy diagram during magnetic field irradiation, and FIG. 6B is an energy diagram after magnetic field irradiation. In each figure, the horizontal axis represents the angle of magnetization (upward magnetization (0 °), downward magnetization (180 °)), and the vertical axis represents energy. In order to reverse the direction of magnetization, it is necessary to give energy exceeding the anisotropic energy Ku of FIG. Will be described.

First, spin wave magnetic temperature (temperature of the spin system) of the magnetic recording portion to between about 10 and about 100ps oscillator 3 by the absorption of microwave magnetic energy generated T _m is increased to about 10 ⁴ K. At this stage, the lattice temperature of the minute portion of the recording track does not rise, so _Ku1 does not decrease. The energy absorbed in the spin system of the recording track is relaxed to the lattice system in a time of about 1 ns, so the temperature of the minute portion rises by about 100 K. At this stage, the anisotropic energy _Ku1 of the recording track decreases (Fig. 6 (a)).

  When the minute part leaves the spin wave oscillator 3 and reaches just below the recording magnetic pole 5 due to the rotation of the magnetic disk, the microwave magnetic field of the recording track stops working and the magnetic temperature returns to room temperature in about 1 ns, but the lattice temperature is Ku1 remains small because it is kept at a high temperature. At this stage, the recording magnetic field is applied to the minute portion, and the writing is finished when the lattice is subsequently cooled (see FIG. 6B).

  Thus, according to the heat-assisted recording head of this embodiment, the medium magnetization can be heated by the near-field using the micro spin wave oscillator 3 as a high-frequency oscillator. At this time, the heating efficiency is dramatically increased by making the oscillation frequency of the spin wave oscillator 3 coincide with or close to the resonance frequency of the magnetic recording unit.

(Second Embodiment)
A similar microwave heating method can also be applied to rewriting magnetic information in MRAM. For example, by combining the heating of the tunnel junction by the spin wave oscillator 3 formed in the vicinity of the magnetic tunnel junction of the memory cell and the current magnetic field from the wiring installed in the vicinity of the tunnel junction, it is smaller than the conventional case. Magnetization reversal can be performed under current.

  A structural example of this memory cell will be described with reference to a schematic cross-sectional view of FIG. Reference numeral 50 in FIG. 7 denotes a storage unit including a tunnel junction. The storage unit includes at least two magnetic layers 51 and 53 and a tunnel layer 52 made of a nonmagnetic dielectric formed therebetween. One of the two magnetic layers 51 and 53 may be a magnetization fixed layer whose magnetization is fixed and which does not rotate substantially even by an external magnetic field such as a current magnetic field, and the other is a magnetization free layer whose magnetization rotates by an external magnetic field. it can. Here, the magnetic layer 51 is assumed to be a magnetization free layer. In the magnetization free layer, magnetization is recorded by a rotating magnetic field included in the plane of FIG. 7 which is generated by passing a current through the wirings 55 and 391 which also serve as electrodes. At this time, the magnetization is easily recorded by heating by the spin wave oscillator 3, and the amount of current for recording can be reduced. In this structure, since the high-frequency magnetic field of the spin wave oscillator 3 needs to spread in a plane perpendicular to the stacking direction, the high-frequency magnetic field extending in the YZ plane is used in the structure of FIG.

  According to the present embodiment, the microwave thermal assist method using a spin wave oscillator can be applied to the writing of the storage magnetization in the MRAM, and the writing of magnetic information to the tunnel junction can be made a small current.

(Example 1)
Next, the creation of the spin torque type transmitter related to the first embodiment and its oscillation frequency will be described with reference to the schematic cross-sectional view of FIG.

First, the laminated structure shown in FIG. 8 was produced on a Si substrate (not shown) by using film formation by sputtering in a magnetic field and electron beam lithography. The thickness of each layer is Cu1 (about 100 nm) / FePt1 (about 50 nm) / Cu2 (about 30 nm) / FePt2 (about 1 nm) / Cu3 (about 10 nm) / Au (about 100 nm) / Cu4 (about 100 nm). About 100 × 100 nm ² was set. FePt 1 and 2 are given perpendicular magnetic anisotropy in which the direction perpendicular to the film surface is the easy axis. The saturation magnetization Ms of FePt 1 and 2 was 800 Gauss, and the anisotropic magnetic field H _K was 26 KOe. The element resistance R of this oscillator was 25Ω, and the MR ratio = ΔR / R was about 7%.

This oscillator was connected to one end of a coplanar guide having a center conductor width of 50 μm. The other end of the coplanar guide was connected to a coaxial cable with a characteristic impedance of 50Ω through a microwave prober. The microwave output from the oscillator is transmitted to the coaxial cable via the prober, and further detected by the spectrum analyzer via the bias tee and preamplifier. When the current density of the direct current flowing through the element exceeded 4 × 10 ⁶ A / cm ² , microwave oscillation at a frequency of 58 GHz was confirmed by a spectrum analyzer. The oscillation intensity increased monotonously with the current density, but the device was destroyed at a current density of ² × 10 ⁸ A / cm ² .

(Example 2)
In Example 2, a spin torque oscillator was manufactured and the oscillation frequency was measured.

Here, an oscillator was fabricated in the same manner as in Example 1 using a [Fe layer (0.5 nm) / Ir layer (0.5 nm)] n laminated film instead of FePt1. When forming the Fe layer / Ir layer laminated film, a magnetic field of 1000 Oe was applied in-plane so that the in-plane anisotropic axes were aligned. The stacking number n was 20 times. The saturation magnetization Ms was 850 Gauss, and the in-plane anisotropic magnetic field H _K was 15 Koe. The element resistance R of this element was 35Ω, and the MR ratio = ΔR / R was about 9%. A bias magnetic field of 500 Oe was applied in the in-plane easy magnetization direction of this element, and the oscillation of the element was observed with a spectrum analyzer in the same manner as in Example 1. Oscillation with a frequency of 35 GHz was confirmed at a DC current density of ² × 10 ⁵ A / cm ² or more.

Example 3
In Example 3, an element was fabricated in the same manner as in Example 2 except that Fe1 (50 nm) and Fe2 (1 nm) were used as the magnetic layer instead of the Fe layer / Ir layer. The saturation magnetization Ms was 1700 gauss, and the in-plane anisotropic magnetic field H _K was 500 Oe. The element resistance R of this element was 15Ω, and the MR ratio = ΔR / R was about 5%. A bias magnetic field of 500 Oe was applied in the in-plane easy magnetization direction of this element, and the oscillation of the element was observed with a spectrum analyzer in the same manner as in Example 1. Oscillation at a frequency of 17 GHz was confirmed at a DC current density of 6 × 10 ⁵ A / cm ² or more.

Example 4
In Example 4, a resonant magnetoresistive effect type spin wave oscillator was manufactured and the oscillation frequency was measured.

A spin wave oscillator shown in the schematic cross-sectional view of FIG. 9 was fabricated on a Si substrate by sputtering in a magnetic field. Cu layers are used as upper and lower electrodes that also serve as heat sinks, FePt (thickness: about 1 nm) is used as a magnetic layer to generate thermal fluctuation of magnetization, and an artificial antiferromagnetic material ([thickness: about 1 nm) is used for the spin wave oscillation layer. Co layer / Pd layer having a film thickness of about 0.5 nm]) ₁₀ . FePt film Example 1 and shows perpendicular magnetic anisotropy that the orthogonal direction is the easy axis in the same manner, the saturation magnetization Ms is 800 gauss, the anisotropy field H _K was 26KOe. On the other hand, the Co film of (Co 1 nm / Pd 0.5 nm) ₁₀ was a perpendicular magnetization film, and the resonance frequency was 52 GHz. When the Co film thickness is 1.5 nm or less, perpendicular magnetization is achieved without applying an external magnetic field.

The microwave oscillation of the oscillator was measured in the same manner as in Example 1 while changing the external magnetic field applied in the direction perpendicular to the film surface with a current of 10 ⁵ A / cm ² flowing through the spin wave oscillator. An oscillation with a frequency of 54 GHz was observed between 660 and 700 Oe.

A perspective view (a) of a magnetic recording / reproducing head and a magnetic recording track recorded according to the first embodiment of the present invention, and a perspective view (b) of a spin wave oscillator and a magnetic recording track The perspective view which shows the spin wave oscillator by the film in-plane magnetization concerning 1st Embodiment is also a schematic diagram The perspective schematic diagram which shows the spin wave oscillator by magnetization perpendicular | vertical to the film surface in connection with 1st Embodiment Upper surface schematic diagram showing recording bit of medium (a), perspective schematic diagram showing magnetization direction (b) Relationship between power supplied from spin wave oscillator to minute part of medium and heat dissipation rate Write process by magnetic head of first embodiment Sectional schematic diagram for demonstrating the heating method of the tunnel junction in connection with the 2nd Embodiment of this invention Sectional schematic diagram showing the spin torque type spin wave oscillator of Example 1 Sectional schematic diagram showing the spin resonance spin wave oscillator of Example 4

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Magnetic recording track 1a, 1b ... Perpendicular magnetization 3 ... Spin oscillator 5 ... Recording magnetic pole 7 ... Sense element 9a, 9b ... Shield

Claims (7)

A recording magnetic pole, a magnetization free layer formed in the vicinity of the recording magnetic pole, the magnetization of which fluctuates, a nonmagnetic layer stacked on the magnetization free layer, and a magnetization fixed in which the magnetization stacked on the nonmagnetic layer is fixed And a pair of electrodes that can be energized in a direction perpendicular to the film surfaces of the magnetization free layer, the nonmagnetic layer, and the magnetization fixed layer, and are injected from the magnetization fixed layer into the magnetization free layer by the energization A magnetic recording head comprising: a spin wave oscillator capable of exciting a spin wave in the magnetization free layer by a spin polarized current. A recording magnetic pole, a magnetization free layer formed in the vicinity of the recording magnetic pole, in which magnetization fluctuates, a nonmagnetic layer stacked on the magnetization free layer, a magnetization fixed layer stacked on the nonmagnetic layer, A pair of electrodes that can be energized in a direction perpendicular to the film surface of the magnetization free layer, the nonmagnetic layer, and the magnetization fixed layer, and injecting a spin fluctuation current from the magnetization free layer into the magnetization fixed layer by the energization A magnetic recording head comprising a spin wave oscillator capable of inducing magnetic resonance or spin waves in the magnetization fixed layer. ^3. The magnetic recording head according to claim 1, wherein the magnetization free layer is a ferromagnetic thin film or a ferromagnetic / antiferromagnetic laminated film having an anisotropic energy of 5 × 10 ⁶ erg / cm ³ or more.   The magnetization fixed layer is an artificial antiferromagnetic material in which a plurality of ferromagnetic materials are stacked via a nonmagnetic material, and the plurality of ferromagnetic materials are antiferromagnetically coupled to each other, and the average thickness of the nonmagnetic material is 3. The magnetic recording head according to claim 1, wherein the magnetic recording head is 1 nm or less.   A magnetic recording apparatus comprising a magnetic recording medium, wherein the oscillation frequency of the spin wave oscillator has an oscillation frequency equal to or close to a magnetic resonance frequency of the magnetic recording medium. A plurality of magnetic layers are laminated via a dielectric layer, and are formed in the vicinity of the magnetic tunnel junction element capable of storing magnetic information by reversal of at least one magnetization of the plurality of magnetic layers, and A magnetization free layer in which magnetization fluctuates, a nonmagnetic layer stacked on the magnetization free layer, a magnetization fixed layer stacked on the nonmagnetic layer, the magnetization fixed layer, the magnetization free layer, the nonmagnetic layer, and A pair of electrodes that can be energized in a direction perpendicular to the film surface of the magnetization fixed layer, and spin into the magnetization free layer by a spin-polarized current injected from the magnetization fixed layer to the magnetization free layer by the energization A magnetic storage device comprising a spin wave oscillator capable of exciting a wave. A plurality of magnetic layers are stacked via a dielectric layer, and are formed in the vicinity of a magnetic tunnel junction element capable of storing magnetic information by reversal of at least one magnetization of the plurality of magnetic layers, and the recording magnetic pole. Fluctuating magnetization free layer, nonmagnetic layer laminated on the magnetization free layer, magnetization fixed layer laminated on the nonmagnetic layer, the magnetization free layer, the nonmagnetic layer, and the magnetization fixed layer A pair of electrodes that can be energized in a direction perpendicular to the plane, and by the energization, a spin fluctuation current is injected from the magnetization free layer into the magnetization fixed layer, and magnetic resonance or spin waves are induced in the magnetization fixed layer. A magnetic storage device comprising a spin wave oscillator capable of performing the same.

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