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WO2016084127A1 - Magnetic sensor - Google Patents

Magnetic sensor Download PDF

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Publication number
WO2016084127A1
WO2016084127A1 PCT/JP2014/081053 JP2014081053W WO2016084127A1 WO 2016084127 A1 WO2016084127 A1 WO 2016084127A1 JP 2014081053 W JP2014081053 W JP 2014081053W WO 2016084127 A1 WO2016084127 A1 WO 2016084127A1
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insulator
ferromagnetic
spin wave
spin
magnetic sensor
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PCT/JP2014/081053
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French (fr)
Japanese (ja)
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雅彦 市村
勝哉 三浦
高橋　宏昌
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株式会社日立製作所
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Priority to JP2016561109A priority Critical patent/JP6267362B2/en
Priority to PCT/JP2014/081053 priority patent/WO2016084127A1/en
Publication of WO2016084127A1 publication Critical patent/WO2016084127A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/09—Magnetoresistive devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/82—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by variation of the magnetic field applied to the device
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00—Galvanomagnetic devices
    • H10N50/10—Magnetoresistive devices

Definitions

  • the present invention relates to a magnetic sensor using a waveguide that propagates spin waves.
  • Electrons have a spin responsible for magnetism in addition to a charge responsible for electrical conduction.
  • attention has been focused on the development of spintronic devices that actively utilize the properties of spins, in addition to electronic devices that use electronic charges.
  • spin injection element tunnel magnetoresistive element
  • Non-Patent Document 1 describes a tunnel magnetoresistive element having a structure in which an insulator and a ferromagnetic metal are sequentially laminated on the upper surface of a “ferromagnetic metal” used in a spin wave waveguide.
  • the same document also describes that the magnetic anisotropy of the spin wave waveguide, which is a ferromagnetic material, changes when an electric field is applied between the ferromagnetic metal and the spin wave waveguide (ferromagnetic metal). .
  • the tunnel magnetoresistive element described in Non-Patent Document 1 can generate a spin wave by controlling the magnetic anisotropy of a magnetic material by applying an electric field, it can be used as a “spin wave generating unit”. it can.
  • a magnetic sensor can be formed by providing a tunnel magnetoresistive element that detects the tunnel magnetoresistive effect at a site different from the spin wave generating portion of the spin wave waveguide. The formation site of the tunnel magnetoresistive element used for detecting the tunnel magnetoresistive effect is called a “spin detector”.
  • a metal is used in the spin wave waveguide.
  • a current flows through the spin wave waveguide. This current becomes a noise source for the tunnel magnetoresistance effect.
  • the spin wave waveguide generates heat due to Joule heat, and a part of energy is dissipated.
  • the present invention provides a magnetic sensor using a spin wave waveguide that can reduce noise and power consumption even when an electric field is applied for controlling anisotropy or when a spin wave is injected for generating a spin wave.
  • a magnetic sensor as one of representative inventions includes: (1) a ferromagnetic insulator; and (2) a first layer stacked in a first region of the ferromagnetic insulator.
  • a spin wave generator having (3) a second nonmagnetic insulator stacked in the second region of the ferromagnetic insulator, and a second ferromagnetic layer stacked on the second nonmagnetic insulator.
  • a spin wave detector having a metal and a voltmeter for detecting a voltage generated between the ferromagnetic insulator and the second ferromagnetic metal.
  • the schematic diagram which shows the structural example of the magnetic sensor of this invention The schematic diagram which shows the structural example of the magnetic sensor which feeds back the signal detected by the spin wave detection part to a spin wave generation part.
  • FIG. 1 shows a configuration example of a magnetic sensor according to the first embodiment.
  • the magnetic sensor of this embodiment includes a ferromagnetic insulator 10, a spin wave generation power source 20 for supplying a current for generating a spin wave, and a spin wave detection voltmeter 30 used for reading information.
  • the ferromagnetic insulator 10 has a shape such as a plate shape, a rod shape, or a column shape.
  • the insulator 11 and the ferromagnetic metal 12 are stacked in order from the lower layer, and together with the spin wave generating power source 20, the spin wave generating unit 25 is configured.
  • the spin wave generating power supply 20 changes the magnetic anisotropy of the ferromagnetic insulator 10 in the vicinity of the interface with the insulator 11 by applying an AC voltage to the ferromagnetic metal 12 joined via the insulator 11. Then, spin waves are generated in the ferromagnetic insulator 10. Furthermore, spin-polarized electrons from the ferromagnetic metal 12 are injected into the ferromagnetic insulator 10 by the applied voltage. When the spin angular momentum of electrons injected from the ferromagnetic metal 12 is transferred to the ferromagnetic insulator 10, torque acts on the spin of the ferromagnetic insulator 10. This torque acts on the spin with changed magnetic anisotropy in the vicinity of the interface of the ferromagnetic insulator 10 to generate a spin wave.
  • the torque acting on the spin by passing the spin angular momentum is a so-called spin transfer torque.
  • the magnetic material sandwiching the insulator 11 is a magnetic tunnel junction made of metal (conventional example)
  • a sufficiently large current can flow through the magnetic tunnel junction (injecting a sufficiently large spin). Therefore, the magnetization of one ferromagnetic metal can be reversed by the spin transfer torque.
  • YIG yttrium iron garnet
  • the magnetic anisotropy of YIG is about ⁇ 600 J / m 3 .
  • the value of this magnetic anisotropy is about 1/1000 of the Co thin film (conventional example). Accordingly, the magnetic anisotropy of the ferromagnetic insulator 10 can be sufficiently changed by electrostatic induction.
  • YIG is also suitable for reducing the applied voltage required for controlling the magnetic anisotropy by the electric field effect.
  • the magnetizations of the ferromagnetic metal 12 and the ferromagnetic insulator 10 are orthogonal to each other. If the purpose is not the magnetization reversal but the induction of spin waves, the value of the current flowing through the thin film of the ferromagnetic insulator 10 is sufficient.
  • the spin wave detection unit 40 is configured in the second region (different from the first region) on the surface of the ferromagnetic insulator 10, the insulator 11 and the ferromagnetic metal 12 are stacked in order from the lower layer, and together with the spin wave detection voltmeter 30, the spin wave detection unit 40 is configured.
  • the spin wave detection voltmeter 30 is for detecting the propagation of the spin wave, and detects the relative direction of magnetization between the ferromagnetic metal 12 and the ferromagnetic insulator 10 by the magnetoresistive effect. As described above, even in the ferromagnetic insulator 10, a slight current can flow on the current path of the spin wave detection unit 40. By flowing a sense current, it is possible to detect a change in the direction of magnetization in the ferromagnetic insulator 10 by the magnetoresistance effect due to the propagation of the spin wave.
  • the magnetic sensor according to the present embodiment does not require an antenna. Therefore, it is possible to realize a magnetic sensor in which the spin wave generator 25 and the spin wave detector 40 are arranged in a minute region.
  • the magnetic sensor according to the present embodiment since no current flows macroscopically in the spin wave waveguide, it is possible to realize a magnetic sensor that generates no Joule heat and has less noise.
  • the magnetic anisotropy of the ferromagnetic insulator 10 constituting the spin wave waveguide is much smaller than that of the conventional example, the applied voltage required for controlling the magnetic anisotropy is small, and the power consumption is small. Can be realized.
  • the magnetic sensor according to the present embodiment can reduce the spin wave attenuation, so that the reach distance of the spin wave can be increased.
  • FIG. 2 shows a configuration example of the magnetic sensor according to the second embodiment.
  • the basic configuration of the magnetic sensor of this embodiment is the same as that of the magnetic sensor according to the first embodiment.
  • the difference is that in the magnetic sensor according to the present embodiment, a function for generating a spin wave with a constant frequency by feeding back the voltage detected by the spin wave detection unit 40 to the spin wave generation unit 25 is provided. This is the point to read out the external magnetic field. For this reason, the magnetic sensor according to the present embodiment is provided with a feedback line.
  • the time scale of the spin precession of a typical ferromagnet is determined by the magnitude of the exchange interaction, and is about 1 GHz and at most about 10 GHz. Based on this precession, if a spin wave generating power supply 20 is given a frequency that causes ferromagnetic resonance using an AC power supply, a resonant spin wave is generated. At this time, the ferromagnetic insulator 10 near the spin wave detector 40 is exposed to an external magnetic field, and the resonance frequency is modulated by the external magnetic field. This modulation can be read by the spin wave detection voltmeter 30.
  • the spin wave detection voltmeter 30 is provided with a feedback function for always generating a spin wave with a constant frequency. Specifically, a feedback line for providing the voltage detected by the spin wave detection voltmeter 30 to the spin wave power supply 20 is provided. Using this feedback function, the magnetic sensor according to the present embodiment detects the magnitude of the external magnetic field.
  • the spin wave generation unit 25 and the spin wave detection unit 40 that constitute the magnetic sensor are spatially separated along the surface of the ferromagnetic insulator 10 that constitutes the spin wave waveguide. It may be set to about 10 ⁇ m to 100 ⁇ m depending on the distance. This distance is the same for the magnetic sensor of the first embodiment.
  • the present invention is not limited to the above-described embodiments, and includes various modifications.
  • lanthanum manganese oxide La_2NiMnO_6, La_2CoMnO_6 may be used.

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  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
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  • Measuring Magnetic Variables (AREA)
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Abstract

This magnetic sensor is configured from: (1) a ferromagnetic insulator; (2) a spin wave generation unit, which has a first non-magnetic insulator laminated in a first region of the ferromagnetic insulator, a first ferromagnetic metal laminated on the first non-magnetic insulator, and a power supply for applying a voltage between the ferromagnetic insulator and the first ferromagnetic metal; and (3) a spin wave detection unit, which has a second non-magnetic insulator laminated in a second region of the ferromagnetic insulator, a second ferromagnetic metal laminated on the second non-magnetic insulator, and a voltmeter for detecting a voltage generated between the ferromagnetic insulator and the second ferromagnetic metal.

Description

磁気センサMagnetic sensor
　本発明は、スピン波を伝播する導波路を利用した磁気センサに関する。 The present invention relates to a magnetic sensor using a waveguide that propagates spin waves.
　電子は、電気伝導を担う電荷に加え、磁性を担うスピンを有している。近年、電子の電荷を活用したエレクトロニクス素子に加え、スピンの性質を積極的に利用したスピントロニクス素子の開発に注目が集まっている。例えばスピンの注入に用いるトンネル磁気抵抗素子（スピン注入素子）が提案されている。 Electrons have a spin responsible for magnetism in addition to a charge responsible for electrical conduction. In recent years, attention has been focused on the development of spintronic devices that actively utilize the properties of spins, in addition to electronic devices that use electronic charges. For example, a tunnel magnetoresistive element (spin injection element) used for spin injection has been proposed.
　非特許文献１には、スピン波導波路に用いる「強磁性金属」の上面に、絶縁体、強磁性金属を順に積層した構造のトンネル磁気抵抗素子が記載されている。また、同文献には、強磁性金属とスピン波導波路（強磁性金属）との間に電界を印加すると、強磁性体であるスピン波導波路の磁気異方性が変化することが記載されている。 Non-Patent Document 1 describes a tunnel magnetoresistive element having a structure in which an insulator and a ferromagnetic metal are sequentially laminated on the upper surface of a “ferromagnetic metal” used in a spin wave waveguide. The same document also describes that the magnetic anisotropy of the spin wave waveguide, which is a ferromagnetic material, changes when an electric field is applied between the ferromagnetic metal and the spin wave waveguide (ferromagnetic metal). .
　前述したように、非特許文献１に記載のトンネル磁気抵抗素子は、電界の印加による磁性体の磁気異方性の制御によりスピン波を生成できるため、「スピン波生成部」として使用することができる。また、スピン波導波路のスピン波生成部とは異なる部位にトンネル磁気抵抗効果を検出するトンネル磁気抵抗素子を設けることで、磁気センサを形成することができる。トンネル磁気抵抗効果の検出に使用されるトンネル磁気抵抗素子の形成部位を「スピン検出部」と呼ぶ。 As described above, since the tunnel magnetoresistive element described in Non-Patent Document 1 can generate a spin wave by controlling the magnetic anisotropy of a magnetic material by applying an electric field, it can be used as a “spin wave generating unit”. it can. In addition, a magnetic sensor can be formed by providing a tunnel magnetoresistive element that detects the tunnel magnetoresistive effect at a site different from the spin wave generating portion of the spin wave waveguide. The formation site of the tunnel magnetoresistive element used for detecting the tunnel magnetoresistive effect is called a “spin detector”.
　ところが、このように非特許文献１に記載の積層構造を有するトンネル磁気抵抗素子を用いて磁気センサを構成すると、スピン波導波路に金属が用いられているため、異方性制御のための電界の印加時やスピン波生成のためのスピン波の注入時に、スピン波導波路に電流が流れてしまう。この電流は、トンネル磁気抵抗効果に対してノイズ源となる。また、電流が流れるとジュール熱によりスピン波導波路が発熱し、一部のエネルギーの散逸が生じる。 However, when a magnetic sensor is configured using the tunnel magnetoresistive element having the laminated structure described in Non-Patent Document 1 as described above, a metal is used in the spin wave waveguide. At the time of application or when a spin wave is injected for generating a spin wave, a current flows through the spin wave waveguide. This current becomes a noise source for the tunnel magnetoresistance effect. Further, when a current flows, the spin wave waveguide generates heat due to Joule heat, and a part of energy is dissipated.
　本発明は、異方性制御のための電界印加時やスピン波生成のためのスピン波注入時にも、ノイズと消費電力が少なく済むスピン波導波路を用いた磁気センサを提供する。 The present invention provides a magnetic sensor using a spin wave waveguide that can reduce noise and power consumption even when an electric field is applied for controlling anisotropy or when a spin wave is injected for generating a spin wave.
　上記解題を解決するために、代表的な発明の一つである磁気センサは、(1)強磁性絶縁体と、(2)前記強磁性絶縁体の第１の領域に積層される第１の非磁性絶縁体と、前記第１の非磁性絶縁体に積層される第１の強磁性金属と、前記強磁性絶縁体と前記第１の強磁性金属との間に電圧を印加する電源とを有するスピン波生成部と、(3)前記強磁性絶縁体の第２の領域に積層される第２の非磁性絶縁体と、前記第２の非磁性絶縁体に積層される第２の強磁性金属と、前記強磁性絶縁体と前記第２の強磁性金属の間に発生する電圧を検出する電圧計とを有するスピン波検出部とを有する。 In order to solve the above problem, a magnetic sensor as one of representative inventions includes: (1) a ferromagnetic insulator; and (2) a first layer stacked in a first region of the ferromagnetic insulator. A nonmagnetic insulator, a first ferromagnetic metal laminated on the first nonmagnetic insulator, and a power source for applying a voltage between the ferromagnetic insulator and the first ferromagnetic metal. A spin wave generator having (3) a second nonmagnetic insulator stacked in the second region of the ferromagnetic insulator, and a second ferromagnetic layer stacked on the second nonmagnetic insulator. A spin wave detector having a metal and a voltmeter for detecting a voltage generated between the ferromagnetic insulator and the second ferromagnetic metal.
　本発明によれば、スピン波導波路に電流がほとんど流れずに済み、低ノイズかつ低消費電力の磁気センサを提供することができる。上記した以外の、課題、構成及び効果は、以下の実施形態の説明により明らかにされる。 According to the present invention, it is possible to provide a magnetic sensor with low noise and low power consumption because almost no current flows through the spin wave waveguide. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.
本発明の磁気センサの構成例を示す模式図。The schematic diagram which shows the structural example of the magnetic sensor of this invention. スピン波検出部で検出された信号をスピン波生成部にフィードバックする磁気センサの構成例を示す模式図。The schematic diagram which shows the structural example of the magnetic sensor which feeds back the signal detected by the spin wave detection part to a spin wave generation part.
　以下、図面に基づいて、本発明の実施の形態を説明する。なお、本発明の実施の態様は、後述する実施例に限定されるものではなく、その技術思想の範囲において、種々の変形が可能である。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiment of the present invention is not limited to the examples described later, and various modifications are possible within the scope of the technical idea.
［実施例１］
［磁気センサの構成］
　図１に、実施例１に係る磁気センサの構成例を示す。本実施例の磁気センサは、強磁性絶縁体１０と、スピン波を生成させるための電流を流すスピン波発生電源２０と、情報の読み出しに用いられるスピン波検出電圧計３０とを備える。強磁性絶縁体１０は、板状、棒状、柱状などの形状を有する。強磁性絶縁体１０の表面の第１の領域には、絶縁体１１及び強磁性金属１２が下層から順に積層され、スピン波発生電源２０と共にスピン波生成部２５を構成する。 [Example 1]
[Configuration of magnetic sensor]
FIG. 1 shows a configuration example of a magnetic sensor according to the first embodiment. The magnetic sensor of this embodiment includes a ferromagnetic insulator 10, a spin wave generation power source 20 for supplying a current for generating a spin wave, and a spin wave detection voltmeter 30 used for reading information. The ferromagnetic insulator 10 has a shape such as a plate shape, a rod shape, or a column shape. In the first region of the surface of the ferromagnetic insulator 10, the insulator 11 and the ferromagnetic metal 12 are stacked in order from the lower layer, and together with the spin wave generating power source 20, the spin wave generating unit 25 is configured.
　スピン波発生電源２０は、絶縁体１１を介して接合された強磁性金属１２に交流電圧を印加することにより、絶縁体１１との界面近傍の強磁性絶縁体１０の磁気異方性を変化させ、強磁性絶縁体１０にスピン波を生成させる。さらに、上記印加電圧により、強磁性金属１２からスピン分極した電子が強磁性絶縁体１０に注入される。強磁性金属１２から注入された電子のスピン角運動量が、強磁性絶縁体１０に受け渡されることにより、強磁性絶縁体１０のスピンにトルクが働く。このトルクが、強磁性絶縁体１０の界面近傍における磁気異方性の変化したスピンに作用することにより、スピン波が生成される。 The spin wave generating power supply 20 changes the magnetic anisotropy of the ferromagnetic insulator 10 in the vicinity of the interface with the insulator 11 by applying an AC voltage to the ferromagnetic metal 12 joined via the insulator 11. Then, spin waves are generated in the ferromagnetic insulator 10. Furthermore, spin-polarized electrons from the ferromagnetic metal 12 are injected into the ferromagnetic insulator 10 by the applied voltage. When the spin angular momentum of electrons injected from the ferromagnetic metal 12 is transferred to the ferromagnetic insulator 10, torque acts on the spin of the ferromagnetic insulator 10. This torque acts on the spin with changed magnetic anisotropy in the vicinity of the interface of the ferromagnetic insulator 10 to generate a spin wave.
　以下、スピン波の導波路として、強磁性絶縁体１０を用いる効果を、同導波路に強磁性金属を用いる場合と比較して説明する。 Hereinafter, the effect of using the ferromagnetic insulator 10 as a spin wave waveguide will be described in comparison with the case of using a ferromagnetic metal in the waveguide.
　スピン角運動量の受け渡しによるスピンに作用するトルクは、いわゆるスピントランスファートルクである。絶縁体１１を挟む磁性体が金属で構成される磁性トンネル接合である場合（従来例）、磁性トンネル接合に十分な大きさの電流を流すことができる（十分な大きさのスピンを注入することができる）ので、そのスピントランスファートルクにより一方の強磁性金属の磁化を反転することができる。 The torque acting on the spin by passing the spin angular momentum is a so-called spin transfer torque. When the magnetic material sandwiching the insulator 11 is a magnetic tunnel junction made of metal (conventional example), a sufficiently large current can flow through the magnetic tunnel junction (injecting a sufficiently large spin). Therefore, the magnetization of one ferromagnetic metal can be reversed by the spin transfer torque.
　一方、強磁性絶縁体１０の場合（実施例）、マクロには電流がほぼ流れず、界面に電場を誘起する（静電誘導）のに留まる。本実施例の場合、スピン波導波路を構成する強磁性絶縁体１０の材料には、例えばYIG（イットリウム鉄ガーネット）を使用する。YIGの磁気異方性は、約－600J/ｍ3である。この磁気異方性の値は、Co薄膜（従来例）の約1000分の１である。従って、静電誘導によっても、強磁性絶縁体１０の磁気異方性は十分に変化させることができる。なお、YIGは、電界効果による磁気異方性の制御に必要な印加電圧の低減にも適している。 On the other hand, in the case of the ferromagnetic insulator 10 (Example), almost no current flows through the macro, and only an electric field is induced at the interface (electrostatic induction). In the case of the present embodiment, for example, YIG (yttrium iron garnet) is used as the material of the ferromagnetic insulator 10 constituting the spin wave waveguide. The magnetic anisotropy of YIG is about −600 J / m 3 . The value of this magnetic anisotropy is about 1/1000 of the Co thin film (conventional example). Accordingly, the magnetic anisotropy of the ferromagnetic insulator 10 can be sufficiently changed by electrostatic induction. YIG is also suitable for reducing the applied voltage required for controlling the magnetic anisotropy by the electric field effect.
　前述したように、強磁性絶縁体１０には、マクロには電流がほぼ流れない。しかし、抵抗は有限値であるため、スピン波発生部２５の電流経路上には僅かながら電流（1μA以下）が流れる。つまり、スピン分極した電流が、強磁性金属１２から絶縁体１１を介して強磁性絶縁体１０に流れ、スピン注入が起こる。電流値が小さくても効率的にスピン注入を行うには、例えば強磁性金属１２にCoFeBを用い、絶縁体１１にMgOを用いることが望ましい。また、スピン注入により、強磁性絶縁体１０に効率的にスピン波を発生するには、強磁性金属１２と強磁性絶縁体１０の磁化がそれぞれ直交するよう設定することが望ましい。目的が磁化反転ではなく、スピン波の誘起であれば、強磁性絶縁体１０の薄膜を流れる電流値で十分である。 As described above, almost no current flows through the ferromagnetic insulator 10 through the macro. However, since the resistance is a finite value, a slight current (1 μA or less) flows on the current path of the spin wave generator 25. That is, the spin-polarized current flows from the ferromagnetic metal 12 to the ferromagnetic insulator 10 through the insulator 11, and spin injection occurs. In order to perform spin injection efficiently even with a small current value, for example, it is desirable to use CoFeB for the ferromagnetic metal 12 and MgO for the insulator 11. In order to efficiently generate spin waves in the ferromagnetic insulator 10 by spin injection, it is desirable to set the magnetizations of the ferromagnetic metal 12 and the ferromagnetic insulator 10 to be orthogonal to each other. If the purpose is not the magnetization reversal but the induction of spin waves, the value of the current flowing through the thin film of the ferromagnetic insulator 10 is sufficient.
　強磁性絶縁体１０の表面の第２の領域（第１の領域とは異なる）には、絶縁体１１及び強磁性金属１２が下層から順に積層され、スピン波検出電圧計３０と共にスピン波検出部４０を構成する。スピン波検出電圧計３０は、スピン波の伝播検出用であり、磁気抵抗効果により強磁性金属１２と強磁性絶縁体１０の間で磁化の相対向きを検出する。上述したように、強磁性絶縁体１０においてもスピン波検出部４０の電流経路上には僅かな電流が流れることが可能である。センス電流を流すことで、スピン波の伝播により強磁性絶縁体１０における磁化の方向変化を磁気抵抗効果により検出することができる。 In the second region (different from the first region) on the surface of the ferromagnetic insulator 10, the insulator 11 and the ferromagnetic metal 12 are stacked in order from the lower layer, and together with the spin wave detection voltmeter 30, the spin wave detection unit 40 is configured. The spin wave detection voltmeter 30 is for detecting the propagation of the spin wave, and detects the relative direction of magnetization between the ferromagnetic metal 12 and the ferromagnetic insulator 10 by the magnetoresistive effect. As described above, even in the ferromagnetic insulator 10, a slight current can flow on the current path of the spin wave detection unit 40. By flowing a sense current, it is possible to detect a change in the direction of magnetization in the ferromagnetic insulator 10 by the magnetoresistance effect due to the propagation of the spin wave.
［まとめ］
　本実施例に係る磁気センサは、アンテナが不要である。このため、スピン波生成部２５とスピン波検出部４０を微小領域内に配置した磁気センサを実現することができる。また、本実施例に係る磁気センサでは、スピン波導波路にマクロ的に電流が流れないためジュール熱の発生が無く、ノイズが少ない磁気センサを実現することができる。また、スピン波導波路を構成する強磁性絶縁体１０の磁気異方性は従来例に比して格段に小さく、磁気異方性の制御に必要な印加電圧が小さく済み、消費電力が小さい磁気センサを実現することができる。また、本実施例に係る磁気センサは、スピン波の減衰が小さく済むため、スピン波の到達距離を長くすることができる。 [Summary]
The magnetic sensor according to the present embodiment does not require an antenna. Therefore, it is possible to realize a magnetic sensor in which the spin wave generator 25 and the spin wave detector 40 are arranged in a minute region. In addition, in the magnetic sensor according to the present embodiment, since no current flows macroscopically in the spin wave waveguide, it is possible to realize a magnetic sensor that generates no Joule heat and has less noise. In addition, the magnetic anisotropy of the ferromagnetic insulator 10 constituting the spin wave waveguide is much smaller than that of the conventional example, the applied voltage required for controlling the magnetic anisotropy is small, and the power consumption is small. Can be realized. In addition, the magnetic sensor according to the present embodiment can reduce the spin wave attenuation, so that the reach distance of the spin wave can be increased.
［実施例２］
［磁気センサの構成］
　図２に、実施例２に係る磁気センサの構成例を示す。本実施例の磁気センサの基本構成は、実施例１に係る磁気センサと同じである。違いは、本実施例に係る磁気センサでは、スピン波検出部４０で検出される電圧をスピン波生成部２５にフィードバックして、一定周波数のスピン波を生成する機能を設け、フィードバック電圧の変化により外部磁場を読み出す点である。このため、本実施例に係る磁気センサには、フィードバック線路が設けられている。 [Example 2]
[Configuration of magnetic sensor]
FIG. 2 shows a configuration example of the magnetic sensor according to the second embodiment. The basic configuration of the magnetic sensor of this embodiment is the same as that of the magnetic sensor according to the first embodiment. The difference is that in the magnetic sensor according to the present embodiment, a function for generating a spin wave with a constant frequency by feeding back the voltage detected by the spin wave detection unit 40 to the spin wave generation unit 25 is provided. This is the point to read out the external magnetic field. For this reason, the magnetic sensor according to the present embodiment is provided with a feedback line.
　典型的な強磁性体のスピン歳差運動の時間スケールは、交換相互作用の大きさで決まり、約１GHｚ、大きくても10GHｚ程度である。この歳差運動をベースとし、スピン波生成電源２０に交流電源を用いて強磁性共鳴を引き起こす周波数を与えると、共鳴的なスピン波が生成される。このとき、スピン波検出部４０の付近の強磁性絶縁体１０は、外部磁場に晒され、上記共鳴周波数が外部磁場により変調される。この変調は、スピン波検出電圧計３０により読み取ることができる。 The time scale of the spin precession of a typical ferromagnet is determined by the magnitude of the exchange interaction, and is about 1 GHz and at most about 10 GHz. Based on this precession, if a spin wave generating power supply 20 is given a frequency that causes ferromagnetic resonance using an AC power supply, a resonant spin wave is generated. At this time, the ferromagnetic insulator 10 near the spin wave detector 40 is exposed to an external magnetic field, and the resonance frequency is modulated by the external magnetic field. This modulation can be read by the spin wave detection voltmeter 30.
　そこで、スピン波検出電圧計３０には、常に一定周波数のスピン波を生成させるためのフィードバック機能が設けられる。具体的には、スピン波検出電圧計３０で検出された電圧をスピン波生電源２０に与えるフィードバック線路を設ける。このフィードバック機能を利用し、本実施例に係る磁気センサは、外部磁場の大きさを検出する。 Therefore, the spin wave detection voltmeter 30 is provided with a feedback function for always generating a spin wave with a constant frequency. Specifically, a feedback line for providing the voltage detected by the spin wave detection voltmeter 30 to the spin wave power supply 20 is provided. Using this feedback function, the magnetic sensor according to the present embodiment detects the magnitude of the external magnetic field.
　磁気センサを構成するスピン波生成部２５とスピン波検出部４０は、スピン波導波路を構成する強磁性絶縁体１０の表面に沿って空間的に隔てられているが、その隔たりはスピン波の到達距離に応じて10μm～100μm程度に設定すれば良い。この距離は、実施例１の磁気センサについても同様である。 The spin wave generation unit 25 and the spin wave detection unit 40 that constitute the magnetic sensor are spatially separated along the surface of the ferromagnetic insulator 10 that constitutes the spin wave waveguide. It may be set to about 10 μm to 100 μm depending on the distance. This distance is the same for the magnetic sensor of the first embodiment.
［まとめ］
　本実施例によれば、フィードバック線路の搭載により、外部磁場の大きさを検出可能な磁気センサを提供することができる。 [Summary]
According to this embodiment, it is possible to provide a magnetic sensor capable of detecting the magnitude of the external magnetic field by mounting the feedback line.
［他の実施例］
　本発明は、上述した実施例に限定されるものでなく、様々な変形例を含んでいる。例えば、強磁性絶縁体の材料として、ガーネット類（例えばY_3(Fe,Al)_50_12、Y_3(Fe,Ga)_50_12）、又は、スピネルフェライト（例えばAFe_20_4（A=Mn, Ni, Cu, Zn）、又は、ランタンマンガン酸化物（La_2NiMnO_6、La_2CoMnO_6）を用いても良い。 [Other embodiments]
The present invention is not limited to the above-described embodiments, and includes various modifications. For example, as a material of the ferromagnetic insulator, garnets (for example, Y_3 (Fe, Al) _50_12, Y_3 (Fe, Ga) _50_12), or spinel ferrite (for example, AFe_20_4 (A = Mn, Ni, Cu, Zn), Alternatively, lanthanum manganese oxide (La_2NiMnO_6, La_2CoMnO_6) may be used.
１０　スピン波導波路
１１　非磁性絶縁体
１２　強磁性金属
２０　スピン波発生電源
２５　スピン波生成部
３０　スピン波検出電圧計
４０　スピン波検出部 DESCRIPTION OF SYMBOLS 10 Spin wave waveguide 11 Nonmagnetic insulator 12 Ferromagnetic metal 20 Spin wave generation power supply 25 Spin wave generation part 30 Spin wave detection voltmeter 40 Spin wave detection part

Claims (4)

  1. 　強磁性絶縁体と、
    　前記強磁性絶縁体の第１の領域に積層される第１の非磁性絶縁体と、前記第１の非磁性絶縁体に積層される第１の強磁性金属と、前記強磁性絶縁体と前記第１の強磁性金属との間に電圧を印加する電源とを有するスピン波生成部と、
    　前記強磁性絶縁体の第２の領域に積層される第２の非磁性絶縁体と、前記第２の非磁性絶縁体に積層される第２の強磁性金属と、前記強磁性絶縁体と前記第２の強磁性金属の間に発生する電圧を検出する電圧計とを有するスピン波検出部と
    　を有する磁気センサ。     A ferromagnetic insulator;
    A first nonmagnetic insulator laminated in a first region of the ferromagnetic insulator; a first ferromagnetic metal laminated on the first nonmagnetic insulator; the ferromagnetic insulator; A spin wave generator having a power source for applying a voltage to the first ferromagnetic metal;
    A second nonmagnetic insulator laminated in a second region of the ferromagnetic insulator; a second ferromagnetic metal laminated on the second nonmagnetic insulator; the ferromagnetic insulator; And a spin wave detector having a voltmeter for detecting a voltage generated between the second ferromagnetic metals.
  2. 　請求項１に記載の磁気センサにおいて、前記強磁性絶縁体を流れる電流が1μA以下である、ことを特徴とする磁気センサ。 2. The magnetic sensor according to claim 1, wherein a current flowing through the ferromagnetic insulator is 1 μA or less.
  3. 　請求項１に記載の磁気センサにおいて、前記スピン波生成部と前記スピン波検出部はスピン波の伝搬方向に10μm以上離れている、ことを特徴とする磁気センサ。 2. The magnetic sensor according to claim 1, wherein the spin wave generation unit and the spin wave detection unit are separated by 10 μm or more in the spin wave propagation direction.
  4. 　請求項１に記載の磁気センサにおいて、前記スピン波検出部で検出される電圧を前記スピン波生成部の前記電源にフィードバックするフィードバック線路を更に有する、ことを特徴とする磁気センサ。 2. The magnetic sensor according to claim 1, further comprising a feedback line that feeds back a voltage detected by the spin wave detection unit to the power source of the spin wave generation unit.
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