JP2012199498A - Spin conduction element and magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spin conduction element for which decline of spin injection efficiency in a high temperature range is suppressed, and a magnetic head.SOLUTION: The spin conduction element is in a structure comprising a channel layer 10 constituted of Si, ferromagnetic layers 20A and 20B formed on the channel layer 10, and tunnel layers 22A and 22B formed so as to be interposed between the channel layer 10 and the ferromagnetic layers 20A and 20B and constituted of BaO. A lattice constant of silicon is 5.4309 Å, and a lattice constant of BaO is 5.5263 Å. The lattice constant of BaO has a difference (mismatch rate) of 1.8% from the lattice constant of the silicon, and the value is about 1/5 compared to a difference in the lattice constant between the silicon and MgO. By adopting BaO as a tunnel material and reducing the difference in the lattice constant between the silicon and the tunnel material compared to a conventional material, decline of the spin injection efficiency in a high temperature range is suppressed.

Description

  The present invention relates to a spin transport element and a magnetic head.

  Recently, the phenomenon of spin conduction in semiconductors has attracted much attention. In particular, silicon is a material that is the center of today's main semiconductor products. If silicon-based spintronics can be realized, new functions can be added to silicon devices without abandoning existing technologies.

  For example, there is a spin-MOSFET disclosed in Patent Document 1 below. Recently, in the following Non-Patent Document 1, the spin conduction phenomenon in silicon at room temperature has been proved, and movement toward application has begun. One of the reasons why the spin conduction phenomenon at room temperature has not been observed until recently is one of the causes that the temperature dependence of the spin injection efficiency into silicon rapidly decreases with increasing temperature (the following non-patent document) 2 and 3). Physically, it is predicted that spin scattering at the interface between the silicon and the tunnel material is a major cause, but no previous cause has been identified.

Note that Al ₂ O ₃ (Non-Patent Document 4), SiO ₂ (Non-Patent Document 5), and MgO (Non-Patent Document 6) are used as tunnel layer materials (tunnel materials) formed on silicon for spin injection. Conventionally known, all are representative substances in spintronics.

JP 2004-111904 A

T. Suzuki et.al., Applied Physics Express 4 (2011), 023003 T. Sasaki et.al., Applied Physics Letter 96 (2010), 122101 T. Sasaki et.al., Applied Physics Letter 98 (2011), 012508 Erveet.al., Applied Physics Letter 91 (2007), 212109 C. H.Li et.al., Applied Physics Letter 95 (2009), 172102 T. Sasaki et.al., Applied Physics Express 2 (2009), 053003 F. J. Jedema Nature London 416 (2002), 713

  Any of the above tunnel materials is stable in amorphous state, but has a lattice constant of 9% or more different from that of silicon or becomes an amorphous film, so that it is difficult to epitaxially grow on silicon. Even if epitaxial growth can be realized, since the difference in lattice constant is large, it is necessary to form a metastable state by forming a lattice mismatch near the growth interface. In such a case, there is a possibility that spins are scattered at a portion where lattice mismatch occurs, and spin injection is not efficiently performed. In particular, the spin injection efficiency may be significantly reduced at high temperatures.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a spin transport element and a magnetic head in which a decrease in spin injection efficiency in a high temperature region is suppressed.

  In order to realize the suppression of the decrease in spin injection in the high temperature region, the inventors focused on the difference in lattice constant between silicon and the tunnel material. In order to remove the lattice mismatch due to the difference in lattice constant, it is necessary to select a tunnel material having a lattice constant close to that of silicon. Many materials are known that have a lattice constant close to that of silicon and epitaxially grow on the silicon. However, in order to solve the above-described problems, it is necessary to select a material that is easy to spin.

  Therefore, the inventors formed a channel layer made of Si, a ferromagnetic layer formed on the channel layer, and formed to be interposed between the channel layer and the ferromagnetic layer, and made of BaO. A new spin transport device with a tunnel layer was discovered.

  Here, the crystal structure of BaO is the same as the crystal structure of conventional MgO, and a coherent tunnel that causes a highly efficient spin tunnel phenomenon can be realized. Further, BaO is an oxide composed of the same alkaline earth material as MgO.

  The lattice constant of silicon is 5.4309３０ and the lattice constant of BaO is 5.5263Å. The lattice constant of BaO has a difference (mismatch rate) of 1.8% with respect to the lattice constant of silicon, and this value is about 1/5 compared with the difference of the lattice constant of silicon and MgO.

  In this way, it is invented that by adopting BaO as a tunnel material and reducing the difference in lattice constant between silicon and the tunnel material as compared with the conventional material, a decrease in spin injection efficiency in a high temperature region is suppressed. They found it after intensive research.

  Further, at least a part of the interface between the channel layer and the tunnel layer may be lattice-matched.

  Furthermore, the aspect whose film thickness of a tunnel layer is 1.0-2.5 nm may be sufficient.

  In addition, the ferromagnetic layer may have a single magnetic domain. The ferromagnetic layer may have a magnetization direction fixed by shape anisotropy or a magnetization direction fixed by an antiferromagnetic film. In other words, the orientation of magnetization may be fixed by a synthetic film.

  The material of the ferromagnetic layer is a metal selected from the group consisting of Al, Cr, Mn, Co, Fe, Ni, Pd, Pt, and Tb, an alloy containing one or more elements of the group, or from the group The aspect which is a compound containing 1 or more elements selected and 1 or more elements selected from the group which consists of B, C, N, Si, and Ge may be sufficient.

  The spin transport device of the present invention can be applied to a magnetic head, a spin transistor, a memory, a sensor, a logic circuit, and the like.

  According to the present invention, a spin transport element and a magnetic head in which a decrease in spin injection efficiency in a high temperature region is suppressed are provided.

FIG. 1 is a schematic cross-sectional view of a magnetic sensor according to an embodiment of the present invention. FIG. 2 is a partial enlarged view of an electrode portion of the magnetic sensor shown in FIG. FIG. 3 is a graph showing the Hanle effect of the magnetic sensor shown in FIG. FIG. 4 is a graph showing the Hanle effect of a magnetic sensor according to the prior art. FIG. 5 is a graph showing the temperature dependence of the spin injection efficiency. FIG. 6 is a graph showing the temperature dependence of the spin injection efficiency normalized at 8K. FIG. 7 is a schematic cross-sectional view of a magnetic sensor having a mode different from that of FIG. FIG. 8 is a schematic sectional view showing a magnetic head including the magnetic sensor shown in FIG. FIG. 9 is a partially enlarged view of an electrode portion having a mode different from that in FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  As shown in FIG. 1, a magnetic sensor 1 that is one of the spin transport elements includes a channel layer 10, a first ferromagnetic layer 20A, and a second ferromagnetic layer 20B, and an external magnetic field in the Z-axis direction. Is detected.

The channel layer 10 extends from the first ferromagnetic layer 20 </ b> A to the second ferromagnetic layer 20 </ b> B, and has a rectangular shape when viewed from the thickness direction of the channel layer 10. The current and spin current flowing in the channel layer 10 are structured to flow mainly in the X-axis direction. The channel layer 10 may be doped with ions for imparting conductivity. The ion concentration can be, for example, 1.0 × 10 ^{15 to} 1.0 × 10 ²² cm ⁻³ . The channel layer 10 is preferably a material having a long spin lifetime, and is made of Si. In addition, the distance from the first ferromagnetic layer 20 </ b> A to the second ferromagnetic layer 20 </ b> B in the channel layer 10 is preferably equal to or shorter than the spin diffusion length of the channel layer 10.

  The first ferromagnetic layer 20 </ b> A and the second ferromagnetic layer 20 </ b> B function as injection electrodes for injecting spins into the channel layer 10 or reception electrodes for detecting spins conducted through the channel layer 10. The first ferromagnetic layer 20 </ b> A is provided on the first region 11 of the channel layer 10. The second ferromagnetic layer 20 </ b> B is provided on the second region 12 of the channel layer 10.

  Each of the first ferromagnetic layer 20A and the second ferromagnetic layer 20B has a rectangular parallelepiped shape with the Y axis direction as the major axis, and the difference in the reversal magnetic field is caused by the difference in the aspect ratio between the Y axis direction and the X axis direction. I'm wearing it. The first ferromagnetic layer 20A and the second ferromagnetic layer 20B can have the same width in the Y-axis direction, and the first ferromagnetic layer 20A and the second ferromagnetic layer 20B can have different widths in the X-axis direction. The coercive force can be made different. As shown in FIG. 1, the magnetization direction G1 of the first ferromagnetic layer 20A can be the same as the magnetization direction G2 of the second ferromagnetic layer 20B, for example. In this case, the magnetization of the first ferromagnetic layer 20A and the second ferromagnetic layer 20B can be easily fixed.

  The first ferromagnetic layer 20A and the second ferromagnetic layer 20B are made of a ferromagnetic material. The material of the first ferromagnetic layer 20A and the second ferromagnetic layer 20B is, for example, TbFeCo, FePt, CoPt, FePd, MnAl, CrCo, and other materials include Al, Cr, Mn, Co, Fe, Ni, A metal selected from the group consisting of Pd, Pt, Tb, an alloy containing one or more elements of the group, or a group consisting of one or more elements selected from the group and B, C, N, Si, Ge It can be set as the compound containing 1 or more elements selected from these.

  The magnetic sensor 1 further includes a first reference electrode 30A and a second reference electrode 30B. The first reference electrode 30 </ b> A is provided on the third region 13 of the channel layer 10. The second reference electrode 30 </ b> B is provided on the fourth region 14 of the channel layer 10. The channel layer 10 extends from the first ferromagnetic layer 20A to the first reference electrode 30A in a direction different from the direction extending from the first ferromagnetic layer 20A to the second ferromagnetic layer 20B. The second ferromagnetic layer 20B extends from the second ferromagnetic layer 20B to the second reference electrode 30B in a direction different from the direction extending from the second ferromagnetic layer 20B to the first ferromagnetic layer 20A. The first reference electrode 30A and the second reference electrode 30B are made of a conductive material, for example, a non-magnetic metal having a low resistance to Si such as Al.

  Between the third region 13 and the fourth region 14, the first region 11 and the second region 12 exist. On the channel layer 10, the first reference electrode 30A, the first ferromagnetic layer 20A, the second ferromagnetic layer 20B, and the second reference electrode 30B are arranged in this order at a predetermined interval in the X-axis direction. ing.

  The magnetic sensor 1 further includes tunnel layers 22A and 22B. The tunnel layers 22A and 22B are provided between the channel layer 10 and the first and second ferromagnetic layers 20A and 20B, respectively. As a result, spin-polarized electrons can be injected from the first ferromagnetic layer 20A and the second ferromagnetic layer 20B to the channel layer 10 with high efficiency, and the potential output of the magnetic sensor 1 can be increased. .

  The tunnel layers 22A and 22B are tunnel barriers made of an insulating material film, and are made of BaO. The thickness of the tunnel layers 22A and 22B is preferably 2.5 nm or less from the viewpoint of suppressing an increase in resistance and functioning as a tunnel insulating layer, and is 1.0 nm or more, which is a thickness at which BaO can be formed as a film. Preferably there is.

  The magnetic sensor 1 further includes an insulating film (or an insulator). The insulating film has a function of preventing the channel layer 10 from being exposed and electrically and magnetically insulating the channel layer 10. The insulating film preferably covers a necessary region of the surface (for example, the lower surface, the side surface, or the upper surface) of the channel layer 10. The insulating film 10 a is provided on the lower surface of the channel layer 10, and the insulating film 10 b is provided on the upper surface of the channel layer 10.

  Specifically, the insulating film 10 b exists between the upper surface of the region existing between the first region 11 and the second region 12 of the channel layer 10 and between the first region 11 and the third region 13 of the channel layer 10. Provided on the upper surface of the region that is between the second region 12 and the fourth region 14. If a wiring connected to the first reference electrode 30A, the first ferromagnetic layer 20A, the second ferromagnetic layer 20B, and the second reference electrode 30B is provided on the insulating film 10b, the spin of the channel layer 10 is formed by this wiring. Can be prevented from being absorbed. In addition, by providing a wiring on the insulating film 10b, it is possible to suppress a current from flowing from the wiring to the channel layer 10.

  Next, an example of the procedure for manufacturing the magnetic sensor 1 will be described.

  First, alignment marks are formed on a previously prepared SOI substrate (Si 100 nm / SiO x 200 nm / Si substrate). Using the alignment mark as a mark, the insulating film 10a is formed on the substrate by, for example, molecular beam epitaxy (MBE).

  Subsequently, the channel layer 10 is formed on the insulating film 10a by, for example, the MBE method. Ions for imparting conductivity are implanted into the channel layer 10 to adjust the conduction characteristics of the channel layer 10. Thereafter, ions are diffused by thermal annealing at a temperature of 900 ° C. Next, deposits, organic substances, and oxide films on the surface of the channel layer 10 were removed by RCA cleaning, and then the surface was terminated with hydrogen using an HF cleaning solution.

Thereafter, the substrate was carried into an MBE apparatus (base vacuum degree: 2.0 × 10 ⁻⁹ Torr or less), and then hydrogen on the substrate surface was desorbed by a flushing process by heating the substrate to form a clean surface. The degree of vacuum during deposition is 5 × 10 ⁻⁸ Torr or less, and film formation is performed in the order of BaO and Fe. That is, on the channel layer 10, a BaO film to be the tunnel layers 22A and 22B and an Fe film (ferromagnetic film) to be the first ferromagnetic layer 20A and the second ferromagnetic layer 20B are formed in this order. As a result, at least a part of the interface between the channel layer 10 and the tunnel layers 22A and 22B is lattice-matched.

  Next, the BaO film and the ferromagnetic film are processed using a mask by, for example, an electron beam (EB) method. For example, as disclosed in JP 2010-199320 A, the channel layer 10 is formed by ion milling or chemical etching using a mask. Further, a BaO film and a ferromagnetic film on the channel layer 10 are formed by, for example, an electron beam (EB) method. By further ion milling or chemical etching, a first ferromagnetic layer 20A is formed on the first region 11 of the channel layer 10 via the tunnel layer 22A, and a tunnel is formed on the second region 12 of the channel layer 10. The second ferromagnetic layer 20B is formed via the layer 22B. If necessary, an antiferromagnetic layer may be further formed on the first ferromagnetic layer 20A and the second ferromagnetic layer 20B by, for example, the MBE method. Then, annealing is performed under a magnetic field in order to fix the magnetization direction of the first ferromagnetic layer 20A or the second ferromagnetic layer 20B. Thereafter, unnecessary tunnel films and ferromagnetic films formed on the channel layer 10 are removed by, for example, ion milling.

  Next, an insulating film 10b is formed on the channel layer 10 from which unnecessary barrier films and ferromagnetic films have been removed. Further, the insulating film 10b on the third region 13 and the fourth region 14 of the channel layer 10 is removed, and the first reference electrode 30A and the second reference electrode 30B are formed, respectively.

  Hereinafter, the function and effect of the magnetic sensor 1 will be described.

  First, the magnetization directions of the first ferromagnetic layer 20A and the second ferromagnetic layer 20B are fixed. In the example shown in FIG. 1, the magnetization direction G1 of the first ferromagnetic layer 20A is fixed in the same direction (Y-axis direction) as the magnetization direction G2 of the second ferromagnetic layer 20B.

  For example, by connecting the first ferromagnetic layer 20A and the first reference electrode 30A to a current source, a detection current can be passed through the first ferromagnetic layer 20A. When a current flows from the nonmagnetic channel layer 10 through the tunnel layer 22A to the first ferromagnetic layer 20A, which is a ferromagnetic material, spin in a direction corresponding to the magnetization direction G1 of the first ferromagnetic layer 20A is generated. The electrons they have are injected into the channel layer 10. The injected spin diffuses toward the second ferromagnetic layer 20B. In this way, the current and spin current flowing in the channel layer 20 can be configured to flow mainly in the X-axis direction.

  Here, when no external magnetic field is applied to the channel layer 10, that is, when the external magnetic field is zero, the direction of spins diffusing in the region between the first region 11 and the second region 12 of the channel layer 10 does not rotate. Accordingly, spins in the same direction as the magnetization direction G2 of the second ferromagnetic layer 20B set in advance diffuse to the second region 12. Therefore, when the external magnetic field is zero, the resistance output or voltage output becomes an extreme value. The maximum value or the minimum value can be taken depending on the direction of current or magnetization. The output can be evaluated by an output measuring instrument such as a voltage measuring instrument connected to the second ferromagnetic layer 20B and the second reference electrode 30B.

  On the other hand, consider a case where an external magnetic field is applied to the channel layer 10. In the example of FIG. 1, the external magnetic field is applied from the Z-axis direction. When an external magnetic field is applied, the direction of the spin diffused in the channel layer 10 rotates around the axial direction (Z-axis direction) of the external magnetic field (so-called Hanle effect). Depending on the relative angle between the rotation direction when the spin diffuses to the second region 12 of the channel layer 10 and the magnetization direction G2 of the second ferromagnetic layer 20B set in advance, that is, the spin, the channel layer 10 And the voltage output and resistance output at the interface of the second ferromagnetic layer 20B are determined. When an external magnetic field is applied, the direction of the spin diffusing through the channel layer 10 rotates, and thus the direction of magnetization G2 of the second ferromagnetic layer 20B is not aligned. Therefore, the resistance output or voltage output takes the maximum value when the external magnetic field is zero, becomes the maximum value or less when the external magnetic field is applied, and applies the external magnetic field when it takes the minimum value when the external magnetic field is zero. Then, it becomes the minimum value or more.

  Therefore, an output peak appears when the external magnetic field is zero, and when the external magnetic field is increased or decreased, the output decreases. That is, since the output changes depending on the presence or absence of an external magnetic field, the magnetic sensor 1 according to this embodiment can be used as a magnetic detection element.

  In the magnetic sensor 1, as described above, the external magnetic field is zero and the output peak appears. Therefore, for example, when the magnetic sensor 1 is applied to a magnetic head or the like and the positive / negative timing of the external magnetic field is read, an output peak appears at the zero point where the magnetic field of the domain wall cancels. . The magnetic sensor 1 is also characterized by no hysteresis.

  As described above, since the tunnel layers 22A and 22B in the magnetic sensor 1 are made of BaO, the following effects can be obtained.

  That is, the lattice constant (5.5263 構成) of BaO constituting the tunnel layers 22A and 22B is very close to the lattice constant (5.4309Å) of silicon as compared with the lattice constant of MgO used conventionally. Thus, it has been newly found that the temperature dependence of spin injection is alleviated by adopting BaO as a tunnel material and reducing the difference in lattice constant between silicon and the tunnel material as compared with the conventional material. It was.

  Here, FIG. 3 is a graph in which the Hanle effect of the spin current when BaO is used as the tunnel material is evaluated at 8K, and FIG. 4 is a Hanle of the spin current when using conventional MgO as the tunnel material. It is the graph which evaluated the effect by 8K.

  In the graphs of FIGS. 3 and 4, although a slight difference in noise is observed, almost the same evaluation results are obtained. The obtained results are analyzed using a known method (for example, the method disclosed in Non-Patent Document 7), and the parameters characterizing the spin conduction are plotted against the temperature change. Is obtained. FIG. 5 shows the temperature dependence of the spin injection efficiency. The spin injection efficiency is a value estimated using the analysis results of FIGS. FIG. 6 is a graph showing the temperature dependence ratio of the spin injection efficiency with 8K as a reference.

  From the graphs showing the temperature dependence in FIGS. 5 and 6, it can be seen that the spin injection efficiency in the low temperature region shows higher characteristics when MgO is used as the tunnel material. However, when MgO is used as the tunnel material, the spin injection efficiency is significantly lowered at a high temperature range. On the other hand, when BaO is used as the tunnel material, the spin injection efficiency at a high temperature region such as MgO does not significantly decrease, and gradually decreases from a low temperature region to a high temperature region. When BaO is used as the tunnel material, spin injection is performed. It can be seen that the temperature dependence of efficiency is moderate. That is, it can be said that the use of the BaO tunnel material is more useful as an actual device than the MgO tunnel material because the spin injection efficiency is maintained to some extent even in a high temperature range.

  The BaO tunnel material has a milder temperature dependence than the MgO tunnel material, which seems to be due to the difference in lattice constant with respect to Si. As described above, the lattice constant of BaO is closer to that of Si. In general, it is known that a difference in lattice constant (lattice mismatch) occurs at an epitaxially grown interface, which causes a decrease in spin injection efficiency.

  In addition, since the reflection intensity which suggests crystallization cannot be obtained from the X-ray diffraction measurement, it is considered that the tunnel layer is not crystallized in the manufacturing process described above. However, even if the tunnel film is not crystallized at the interface between the tunnel layer and Si, which contributes most to spin scattering, it is considered that there is an influence due to the difference in lattice constant.

  The magnetic sensor 1 of the present invention can be applied to a magnetic head, a spin transistor, a memory, a sensor, a logic circuit, and the like. When optimizing the magnetic head, it is preferable that the external magnetic field is incident from the Y-axis direction of FIG. 1, and in this case, the ferromagnetic layers 20A and 20B are formed like the magnetic sensor 1A shown in FIG. It is fixed to the X axis (or Z axis). As a method for fixing the magnetization directions of the ferromagnetic layers 20A and 20B, an antiferromagnetic film that fixes the magnetization direction in the X direction or a perpendicular magnetization film having magnetic anisotropy in the Z direction is preferable.

  FIG. 8 is a schematic sectional view showing a magnetic head 100A which is a thin film magnetic recording / reproducing head. The magnetic sensor 1A shown in FIG. 7 described above can be applied to the read head unit 100a of the magnetic head 100A. The magnetic head 100 </ b> A performs magnetic information recording and reading operations at a position where its air bearing surface (air bearing surface) ABS is disposed to face the recording surface 120 a of the magnetic recording medium 120. The front end surface of the channel layer 10 of the magnetic sensor 1A described above (the front surface of the channel layer 10 in FIG. 7) is disposed so as to correspond to the air bearing surface ABS.

  The magnetic recording medium 120 includes a recording layer 120b having a recording surface 120a and a soft magnetic backing layer 120c laminated on the recording layer 120b, and the magnetic recording medium 120 is magnetic in the direction indicated by the Z-axis direction in FIG. Progress relative to the head 100A. The magnetic head 100 </ b> A includes a recording head unit 100 b that performs recording on the magnetic recording medium 120 in addition to the reading head unit 100 a that reads records from the magnetic recording medium 120. The read head unit 100a and the recording head unit 100b are provided on the substrate 101 and are covered with a nonmagnetic insulating layer such as alumina.

  As shown in FIG. 8, a recording head unit 100b for writing is provided on the reading head unit 100a. In the recording head portion 100b, a contact portion 132 and a main magnetic pole 133 are provided on the return yoke 130, and these form a magnetic flux path. A thin film coil 131 is provided so as to surround the contact portion 132. When a recording current is passed through the thin film coil 131, a magnetic flux is released from the tip of the main magnetic pole 133, and information is recorded on the recording layer 120b of the magnetic recording medium 120 such as a hard disk. Can be recorded. As described above, the magnetic head 100A capable of detecting a magnetic flux from a minute region such as a recording medium can be provided by using the magnetic sensor 1 of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the electrode structure in the portions of the first ferromagnetic layer 20A and the second ferromagnetic layer 20B can be a laminated structure magnetized by a synthetic film as shown in FIG. 9 is a structure in which BaO (film thickness 1.2 nm), Fe (film thickness 10 nm), Ru (film thickness 1.5 nm), and Ta (film thickness 1 nm) are sequentially formed on Si. Corresponding to the channel layer 10, the tunnel layers 22 A and 22 B, the ferromagnetic layers 20 A and 20 B, the protective film layer 24, the Ru layer 26, and the ferromagnetic layer 28.

  The magnetization directions of the first ferromagnetic layer 20A and the second ferromagnetic layer 20B are fixed by an antiferromagnetic layer or shape anisotropy provided on the first ferromagnetic layer 20A and the second ferromagnetic layer 20B. May be. For example, in the first ferromagnetic layer 20A and the second ferromagnetic layer 20B, the difference in the reversal magnetic field is given by the difference in the aspect ratio between the X-axis direction and the Y-axis direction. Alternatively, the first ferromagnetic layer 20A and the second ferromagnetic layer 20B may be provided with an antiferromagnetic layer for fixing the magnetization direction. In this case, the first ferromagnetic layer 20A or the second ferromagnetic layer 20B having a higher coercive force in one direction than when no antiferromagnetic layer is provided can be obtained.

  DESCRIPTION OF SYMBOLS 1, 1A ... Magnetic sensor, 10 ... Channel layer, 20A, 20B ... Ferromagnetic layer, 22A, 22B ... Tunnel layer, 30A, 30B ... Reference electrode, 100A ... Magnetic head.

Claims (9)

A channel layer made of Si;
A ferromagnetic layer formed on the channel layer;
A spin transport device, comprising: a tunnel layer formed of BaO and interposed between the channel layer and the ferromagnetic layer.   The spin transport device according to claim 1, wherein at least a part of an interface between the channel layer and the tunnel layer is lattice-matched.   The spin transport device according to claim 1 or 2, wherein the tunnel layer has a thickness of 1.0 to 2.5 nm.   The spin transport device according to any one of claims 1 to 3, wherein the ferromagnetic layer has a single domain.   The spin transport device according to claim 4, wherein the magnetization direction of the ferromagnetic layer is fixed by shape anisotropy.   The spin transport device according to claim 4, wherein the ferromagnetic layer is an antiferromagnetic film and has a fixed magnetization direction.   The spin transport device according to claim 4, wherein the ferromagnetic layer has a magnetization orientation fixed by a synthetic film.   The material of the ferromagnetic layer is a metal selected from the group consisting of Al, Cr, Mn, Co, Fe, Ni, Pd, Pt, Tb, an alloy containing one or more elements of the group, or selected from the group The spin conduction according to any one of claims 1 to 7, which is a compound comprising one or more elements selected from the group consisting of B, C, N, Si, and Ge. element.   A magnetic head comprising the spin transport device according to claim 1.

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