WO2023234269A1 - 磁気メモリ素子、情報処理システム、及び磁気メモリ素子の制御方法 - Google Patents

磁気メモリ素子、情報処理システム、及び磁気メモリ素子の制御方法 Download PDF

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WO2023234269A1
WO2023234269A1 PCT/JP2023/019977 JP2023019977W WO2023234269A1 WO 2023234269 A1 WO2023234269 A1 WO 2023234269A1 JP 2023019977 W JP2023019977 W JP 2023019977W WO 2023234269 A1 WO2023234269 A1 WO 2023234269A1
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layer
antiferromagnetic
magnetic
spin
memory element
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French (fr)
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知 中▲辻▼
友也 肥後
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University of Tokyo NUC
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University of Tokyo NUC
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Priority to US18/869,003 priority patent/US20250351732A1/en
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    • 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
    • H10N50/80—Constructional details
    • H10N50/85—Materials of the active region
    • 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
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
    • G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
    • G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
    • G11C11/161—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
    • G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
    • G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
    • G11C11/165—Auxiliary circuits
    • G11C11/1659—Cell access
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
    • G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
    • G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
    • G11C11/165—Auxiliary circuits
    • G11C11/1673—Reading or sensing circuits or methods
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
    • G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
    • G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
    • G11C11/165—Auxiliary circuits
    • G11C11/1675—Writing or programming circuits or methods
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
    • G11C11/18—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using Hall-effect devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10B—ELECTRONIC MEMORY DEVICES
    • H10B61/00—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
    • H10B61/20—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices comprising components having three or more electrodes, e.g. transistors
    • H10B61/22—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices comprising components having three or more electrodes, e.g. transistors of the field-effect transistor [FET] type

Definitions

  • the present invention relates to a magnetic memory element, an information processing system, and a method of controlling a magnetic memory element.
  • Magnetic random access memory (MRAM) using ferromagnetic materials is nonvolatile, and is therefore attracting attention as a memory that realizes information processing with low power consumption.
  • various semiconductor manufacturers are adopting MRAM as a replacement for volatile memories such as static random access memory (SRAM).
  • SRAM static random access memory
  • Examples of such MRAM include STT-MRAM, which uses spin transfer torque (STT) to reverse the magnetization of a ferromagnetic material, and SOT-MRAM, which uses spin-orbit torque (SOT) to reverse the magnetization of a ferromagnetic material.
  • STT-MRAM spin transfer torque
  • SOT-MRAM spin-orbit torque
  • the magnetization reversal speed remains at around 1 nanosecond.
  • the THz band (picosecond ) has the problem of not being able to respond.
  • the present invention has been made in view of the above problems, and an object of the present invention is to enable high-speed writing and reading operations using a magnetic memory element using an antiferromagnetic material.
  • a magnetic memory element has an antiferromagnetic layer that has uniaxial strain, is made of an antiferromagnetic metal containing manganese, and has an antiferromagnetic layer in which the magnetic order of the antiferromagnetic metal can be controlled by spin torque. .
  • a magnetic memory element is made of a substance exhibiting a spin Hall effect, and includes a spin Hall layer in which a spin current is generated when a write current flows in an in-plane direction, and a spin Hall layer laminated on the spin Hall layer, which is uniaxially strained. a free layer that includes an antiferromagnetic metal containing manganese and in which the magnetic order of the antiferromagnetic metal can be reversed by spin-orbit torque generated by a spin current, and a nonmagnetic layer laminated on the free layer.
  • a reference layer laminated on the nonmagnetic layer made of a ferromagnetic metal or an antiferromagnetic metal containing manganese, and in which the magnetic order of the ferromagnetic metal or the antiferromagnetic metal is fixed.
  • a magnetic memory element includes a reference layer made of a ferromagnetic metal or an antiferromagnetic metal containing manganese, and a reference layer in which the magnetic order of the ferromagnetic metal or the antiferromagnetic metal is fixed.
  • a reference layer made of a ferromagnetic metal or an antiferromagnetic metal containing manganese
  • a reference layer in which the magnetic order of the ferromagnetic metal or the antiferromagnetic metal is fixed.
  • which includes a nonmagnetic layer laminated on a reference layer and an antiferromagnetic metal laminated on the nonmagnetic layer has uniaxial strain, and contains manganese, and when a write current flows in the direction perpendicular to the plane, spin transfer occurs. and a free layer in which the magnetic order of the antiferromagnetic metal can be reversed by torque.
  • An information processing system is an information processing system including the above-described magnetic memory element.
  • An information processing system is an information processing system including a magnetic memory device having a plurality of the above-described magnetic memory elements arranged in a matrix.
  • a method for controlling a magnetic memory element is a method for controlling a magnetic memory element including an antiferromagnetic layer having uniaxial strain and made of an antiferromagnetic metal containing manganese, the method comprising: Controlling magnetic order in antiferromagnetic metals by torque.
  • a method for controlling a magnetic memory element includes a spin Hall layer made of a substance exhibiting a spin Hall effect, and an antiferromagnetic material laminated on the spin Hall layer, having uniaxial strain and containing manganese.
  • a free layer containing metal, a nonmagnetic layer laminated on the free layer, and a ferromagnetic metal or an antiferromagnetic metal containing manganese laminated on the nonmagnetic layer, and the ferromagnetic metal or antiferromagnetic material A method for controlling a magnetic memory element comprising a reference layer in which magnetic order of metal is fixed, the method comprising: generating a spin current by flowing a write current in an in-plane direction in a spin hole layer; reversing the magnetic order of the antiferromagnetic metal of the free layer by spin-orbit torque.
  • a method for controlling a magnetic memory element is a method for controlling a magnetic memory element made of a ferromagnetic metal or an antiferromagnetic metal containing manganese, and in which the magnetic order of the ferromagnetic metal or the antiferromagnetic metal is fixed.
  • Control of a magnetic memory element comprising a reference layer, a nonmagnetic layer laminated on the reference layer, and a free layer laminated on the nonmagnetic layer, having uniaxial strain and containing an antiferromagnetic metal containing manganese.
  • the method reverses the magnetic order of antiferromagnetic metal in the free layer by applying a write current in a direction perpendicular to the plane of a magnetic memory element using spin transfer torque.
  • a magnetic memory element includes an antiferromagnetic layer that has uniaxial strain and is made of an antiferromagnetic metal containing manganese, and the magnetic order of the antiferromagnetic metal can be controlled by spin torque. Therefore, the magnetization reversal speed can be increased, and high-speed writing and reading operations can be performed.
  • FIG. 1 is a cross-sectional view of a magnetic memory element according to a first embodiment of the present invention.
  • FIG. 2 is a schematic diagram showing the crystal structure and magnetic structure of Mn 3 Sn.
  • FIG. 3 is a schematic diagram for explaining control of the magnetic state when in-plane tensile strain exists in the Mn 3 Sn layer of the MgO substrate/W/Mn 3 Sn multilayer film. It is a graph showing the X-ray diffraction pattern of the 2 ⁇ / ⁇ scan for the MgO substrate/W/Mn 3 Sn/MgO sample and the MgO substrate. 3 is a graph showing ⁇ scan X-ray diffraction patterns for an Mn 3 Sn layer, a W layer, and an MgO substrate.
  • FIG. 1 is a cross-sectional transmission electron microscope (TEM) image of a Mn 3 Sn layer.
  • FIG. 3 is a schematic diagram for explaining tensile strain of an Mn 3 Sn layer in an epitaxial film.
  • FIG. 2 is a schematic diagram showing a binary state of a Kagome layer stabilized by epitaxial uniaxial tensile strain ( ⁇ >0) in a Mn 3 Sn layer.
  • FIG. 2 is a schematic diagram showing the configuration of a magnetic memory element having a Hall bar structure.
  • FIG. 2 is a schematic diagram showing the configuration of two Mn 3 Sn samples (M1 and M2) with different compression directions. It is a graph showing the magnetic field dependence of magnetization at various uniaxial stresses for each sample. It is a graph showing the temperature dependence of magnetization at various uniaxial stresses for each sample.
  • FIG. 2 is a schematic diagram for explaining measurement of the Hall effect on two Mn 3 Sn samples (H1 and H2) with different strain directions. It is a graph showing magnetic field dependence of Hall resistivity at various strains for sample H1. It is a graph showing magnetic field dependence of Hall resistivity at various strains for sample H2.
  • FIG. 7 is a cross-sectional view of a magnetoresistive element constituting a magnetic memory element according to a third embodiment of the present invention. 17 is a schematic diagram for explaining the resistance state of the magnetoresistive element of FIG. 16.
  • FIG. 1 is a schematic diagram showing the configuration of a magnetic memory element of SOT-MRAM.
  • FIG. 2 is a schematic diagram showing the configuration of a magnetic memory element of STT-MRAM.
  • a multilayer film may be expressed by the substance of each layer that constitutes the multilayer film.
  • this multilayer film is expressed as "substance a/substance b/substance c.”
  • the thickness (nm) of each layer may be written in parentheses after the substance name. For example, a layer having a thickness of ti (nm) and made of substance j is expressed as "substance j (ti)".
  • an antiferromagnetic material is used instead of a ferromagnetic material in order to realize a nonvolatile memory that can operate at high speed.
  • antiferromagnetic materials have a spin response speed that is two to three orders of magnitude faster than ferromagnetic materials in the THz band (picoseconds), and the interaction between magnetic materials is small, making magnetic devices even faster. This is because there is a possibility of high integration.
  • the magnetic memory element 100 includes a substrate 10, a spin Hall layer 12 on the substrate 10, and an antiferromagnetic layer 14 on the spin Hall layer 12.
  • the substrate 10 is made of an insulator such as MgO.
  • the spin Hall layer 12 is made of a substance exhibiting a spin Hall effect (spin Hall material), such as a nonmagnetic heavy metal such as tantalum (Ta), tungsten (W), or platinum (Pt), or a chalcogenide material such as a topological insulator.
  • Consisting of The antiferromagnetic layer 14 is a thin film made of antiferromagnetic metal containing manganese (Mn).
  • Examples of gamma-type Mn alloys include Mn 1-x Fe x , Mn 1-x Rh x , Mn 1-x Pd x , and the like.
  • a mixture of different Mn 3 X for example, a mixture of Mn 3 Sn and Mn 3 Ga
  • a mixture of Mn 3 A mixture of these materials may be used for the antiferromagnetic layer 14.
  • the magnetic memory element 100 shown in FIG. 1 a configuration in which a spin Hall layer is stacked on an antiferromagnetic layer (substrate/antiferromagnetic layer/spin Hall layer) may be adopted. Further, the antiferromagnetic layer may be sandwiched between two spin Hall layers made of spin Hall materials having spin Hall angles of different signs. Below, the magnetic memory element 100 shown in FIG. 1 will be mainly described.
  • the magnetic memory element 100 Next, a method for manufacturing the magnetic memory element 100 will be explained.
  • a W (7 nm)/Mn 3 Sn (30 nm)/MgO (5 nm) multilayer film is formed on an MgO (110) substrate.
  • the MgO (5 nm) layer is provided to prevent oxidation of the Mn 3 Sn layer.
  • the thickness (nm) of each layer of the magnetic memory element 100 is an example, and is not limited.
  • the MgO substrate is annealed at 800° C. for 10 minutes in an ultra-high vacuum chamber.
  • a W (7 nm)/Mn 3 Sn (30 nm)/MgO (5 nm) multilayer film was deposited on an MgO (110) substrate by molecular beam epitaxy (MBE) under ultra-high vacuum with a base pressure of 2 ⁇ 10 -8 Pa. Created.
  • a W (7 nm) layer is deposited at 300°C at a rate of 0.1 ⁇ /s and then annealed at 800°C for 10 minutes.
  • the Mn 3 Sn (30 nm) layer is fabricated by co-evaporation of Mn and Sn at a rate of 0.25 ⁇ /s.
  • a Mn 3 Sn (5 nm) layer is deposited at room temperature and then annealed at 400°C.
  • An additional Mn 3 Sn (25 nm) layer is then deposited at about 260°C.
  • a clear striped pattern can be observed from an in-situ reflection high-energy electron diffraction (RHEED) image. This indicates that the W layer and the Mn 3 Sn layer are epitaxially grown in this manufacturing process.
  • RHEED reflection high-energy electron diffraction
  • a MgO layer is fabricated at room temperature at a rate of 0.1 ⁇ /s.
  • the MgO (110) substrate/W (7 nm)/Mn 3 Sn (30 nm)/MgO (5 nm) multilayer film is annealed at 650° C. for 30 minutes. Note that by using a similar baking process in the sputtering method instead of the MBE method, a multilayer film having the same characteristics as the multilayer film produced by the MBE method can be manufactured.
  • Mn 3 Sn is an antiferromagnetic material that has a triangular-based crystal structure called a kagome lattice, and as shown in FIG. 2, it has a structure in which kagome lattices are stacked in the [0001] direction. Due to geometric frustration, Mn located at the apex of the Kagome lattice has a non-collinear magnetic structure in which the magnetic moments (orientations of localized spins) are tilted 120 degrees to each other at temperatures below 420 K. shows.
  • the six spin units of three types arranged on a two-layered Kagome lattice form a spin order called a cluster magnetic octupole, which is represented by a hexagon.
  • This non-collinear magnetic structure can be considered as a ferromagnetic order of cluster magnetic octupole.
  • This ferromagnetic order macroscopically breaks time reversal symmetry.
  • the cluster magnetic octupole corresponds to Weyl points, which are topological electronic structures, and the orientation of the virtual magnetic field in momentum space (equivalent to 100 to 1000 Tesla (T) in real space), and the cluster magnetic octupole
  • T Tesla
  • the response derived from the Weyl points and the virtual magnetic field can be controlled by the orientation of the poles.
  • the magnetic structure as shown in FIG. 2 has orthorhombic symmetry, and only one of the three magnetic moments of Mn located at the vertices of the triangle is parallel to the axis of easy magnetization. Since the other two magnetic moments cant with respect to the easy axis of magnetization, it is thought that a weak ferromagnetic moment is induced.
  • An antiferromagnetic material that has minute magnetization due to a canted magnetic moment is called a canted antiferromagnet.
  • the crystal orientation of Mn 3 Sn plays an important role in enhancing the read signal of a magnetic memory element. For example, in the measurement of the anomalous Hall effect described below, only crystal grains in which the magnetic order of the cluster magnetic octupole has a component in the perpendicular direction (perpendicular to the surface of the substrate 10) contribute to the Hall voltage.
  • a tensile strain ⁇ in the [2-1-10] direction is generated in the Mn 3 Sn layer, as shown in FIG.
  • the magnetic order of the cluster magnetic octupole is oriented perpendicular to the plane. This determines the binary state (upward, downward) on the Kagome layer (see FIG. 6B).
  • FIG. 4A shows 2 ⁇ / ⁇ scan X-ray diffraction patterns for the MgO (110) substrate/W (7 nm)/Mn 3 Sn (30 nm)/MgO (5 nm) sample and the MgO (110) substrate.
  • the temperature T A when annealing the multilayer film after forming all layers is 650°C and 700°C.
  • the X-ray diffraction pattern is shown.
  • FIG. 4A also shows the theoretical spectra of D0 19 type Mn 3 Sn and ⁇ -W. Further, FIG. 4B shows X-ray diffraction patterns of ⁇ scans for the ⁇ 02-21 ⁇ plane of the Mn 3 Sn layer, the ⁇ 110 ⁇ plane of the W layer, and the ⁇ 200 ⁇ plane of the MgO substrate.
  • the ⁇ 110 ⁇ peak of the W layer and the ⁇ 021 ⁇ peak of the Mn 3 Sn layer appear to be shifted by 90 degrees from the ⁇ 200 ⁇ peak of the MgO substrate.
  • the Mn 3 Sn layer is selectively oriented as MgO(110)[001]
  • FIG. 5 shows the atomic arrangement of the Mn 3 Sn layer in the MBE grown film.
  • the interatomic distances d 1 and d 2 in each triangle constituting the hexagon, and the angle ⁇ 12 can be determined experimentally.
  • Other interatomic distance d 3 and length d in parallel to the [2-1-10] direction (x direction) can be determined from d 1 , d 2 , and ⁇ 12 .
  • the Mn 3 Sn layer in the MBE-grown film has almost the same d 1 but longer d 2 and larger ⁇ 12 , increasing d in from 4.251 ⁇ to 4.25 ⁇ . It has increased to 261 ⁇ . This indicates that about 0.2% tensile strain (epitaxial strain) ⁇ exists in the [2-1-10] direction (x direction).
  • the presence of similar strain can also be evaluated from a cross-sectional transmission electron microscope (TEM) image of the Mn 3 Sn layer shown in FIG. 4C.
  • the diamonds represent Mn 3 Sn unit cells.
  • the spin structure on the Kagome layer has a magnetic order of six equivalent ⁇ 2-1-10 ⁇ cluster magnetic octopoles, as shown in FIG. 6A. It assumes six degenerate states oriented along.
  • the magnetic order of the cluster magnetic octupole changes along the perpendicular direction, as shown in Figure 6B. It takes a binary state of parallel (upward) and antiparallel (downward) to the [01-10] direction. Thereby, binary data (“0” and “1”) can be represented.
  • FIG. 7 shows the configuration of a magnetic memory element 100 having a Hall bar structure. Electrodes 16a and 16b made of Au/Ti are arranged at both ends of the sample in the longitudinal direction (x direction) of the magnetic memory element 100, and electrodes 18a and 18b made of Au/Ti are arranged in the transverse direction (y direction). is located. A write current I write or a read current I read flows between the electrodes 16a and 16b, and a Hall voltage VH is detected between the electrodes 18a and 18b.
  • a write current I write pulse current
  • a spin current is generated in the perpendicular direction (z direction) due to the spin Hall effect, and the SOT acts on the magnetization of the antiferromagnetic layer 14, thereby reversing the magnetization.
  • Hx weak bias magnetic field
  • the direction of magnetization of the antiferromagnetic layer 14 can be controlled by the direction of the write current I write .
  • the magnetization is reversed from the +z direction (“1”) to the ⁇ z direction (“0”), and when a write current I write is applied in the ⁇ x direction, the magnetization changes to ⁇ It is reversed from the z direction (“0”) to the +z direction (“1”).
  • a read current I read DC
  • a Hall voltage V H is generated in the y direction due to the abnormal Hall effect.
  • the sign of the Hall voltage V H is determined by the z component of the magnetization of the antiferromagnetic layer 14 . For example, when the magnetization of the antiferromagnetic layer 14 is oriented in the +z direction, it corresponds to "1", and when it is oriented in the -z direction, it corresponds to "0".
  • the multilayer film of the magnetic memory element 100 used in the measurement was W (7 nm)/Mn 3 Sn (30 nm) on an MgO substrate.
  • FIG. 8A shows the change in the Hall voltage V H with respect to the vertical magnetic field H (magnetic field in the z direction) at room temperature. As shown in FIG. 8A, a clear hysteresis of the Hall voltage V H is observed.
  • the difference (Hall voltage change) ⁇ V H field at zero magnetic field between the Hall voltage V H when the magnetic field H is swept from negative to positive and the Hall voltage V H when the magnetic field H is swept from positive to negative is approximately 40 ⁇ V It is.
  • FIG. 8B shows the Hall voltage V H with respect to the write current I write at room temperature when a bias magnetic field ⁇ 0 H of 0.1 T is applied in the x direction to a W (7 nm)/Mn 3 Sn (30 nm) multilayer film. shows the change in
  • a read current I read is applied after a write current I write is applied.
  • a clear hysteresis is observed, and the jump in the Hall voltage V H due to the write current I write exceeding the threshold corresponds to a reversal of the magnetic order (magnetization reversal) of the cluster magnetic octupole.
  • the difference (Hall voltage change) between the Hall voltage V H when the write current I write is swept from negative to positive and the Hall voltage V H when the write current I write is swept from positive to negative is expressed as ⁇ V H current . do.
  • indicates the ratio of actually reversed magnetic domains (reversal ratio) to the total reversible magnetic domains. Also in FIG. 8B, since ⁇ V H current is approximately 40 ⁇ V, ⁇ V H current /
  • FIGS. 8A and 8B show that in the Mn 3 Sn layer, perpendicular magnetic anisotropy is effective due to epitaxial strain in the in-plane direction. This can be considered to be due to the control of magnetic anisotropy by the piezomagnetic effect described in the second embodiment below. This makes it possible to obtain a stable binary antiferromagnetic state, eliminate signal variations even when the magnetic memory element 100 is miniaturized, and improve operational reliability.
  • the magnetic memory element according to the first embodiment when there is epitaxial strain in the in-plane direction of the antiferromagnetic layer, the cluster magnetic eight characterizing the antiferromagnetic state in the direction perpendicular to the strain direction.
  • the magnetic order of the poles can be oriented and define binary states. Therefore, a magnetic memory element using an antiferromagnetic material enables high-speed write and read operations.
  • the magnetic memory element according to the second embodiment also has the same configuration as the magnetic memory element 100 (FIG. 1) according to the first embodiment, and the material of the multilayer film constituting the magnetic memory element is also the same as that of the first embodiment. The same is true.
  • the second embodiment will also be described using Mn 3 Sn as an example of the antiferromagnetic metal.
  • Both samples M1 and M2 are single crystals made of Mn 3 Sn , and as shown in FIG. This is a sample to which a uniaxial stress ⁇ yy of ⁇ yy was applied from above and below. Further, a magnetic field H x in the [2-1-10] direction (+x direction) and a magnetic field H y in the [01-10] direction (+y direction) are applied to the samples M1 and M2, respectively. Uniaxial stress is applied to these samples using, for example, a piston cylinder type pressure cell described in the following non-patent literature. Kittaka, S., Taniguchi, H., Yonezawa, S., Yaguchi, H. & Maeno, Y. “Higher-Tc superconducting phase in Sr 2 RuO 4 induced by uniaxial pressure” Phys. Rev. B 81, 180510 (2010 )
  • FIG. 13 shows the uniaxial stress dependence of spontaneous magnetization MS and magnetic susceptibility ⁇ at 300 K for samples M1 and M2.
  • data black circles
  • data white circles
  • M S of sample M1 is 3.6 m ⁇ B /f. u.
  • the coercive force is very small at 0.03T.
  • M S of sample M1 is 10.7 m ⁇ B /f. u. This represents an approximately three-fold increase.
  • the magnetization M increases linearly with respect to the magnetic field, except in the low magnetic field region, and the slope thereof represents the magnetic susceptibility ⁇ .
  • samples H1 and H2 are both samples of single-crystal antiferromagnetic layers 20 made of Mn 3 Sn, and sample H1 has a strain ⁇ xx in the x direction and the y direction, respectively.
  • a magnetic field H y is applied, and a strain ⁇ yy and a magnetic field H x are applied to the sample H2 in the y direction and the x direction, respectively.
  • a piezo-type strain device described in the following non-patent literature is used to measure the anomalous Hall effect under various strains. Hicks, C. W., Barber, M. E., Edkins, S. D., Brodsky, D. O. & Mackenzie, A. P. “Piezoelectric-based apparatus for strain tuning” Rev. Sci. Instrum. 85, 065003 (2014)
  • a current I flows through the samples H1 and H2 along the strain direction, and a Hall voltage V H perpendicular to the current I in the plane is measured.
  • V H ⁇ I/t.
  • FIG. 15A shows the magnetic field dependence of the Hall resistivity ⁇ zx at 300 K at various strains ⁇ xx for sample H1.
  • the Hall resistivity ⁇ zy of sample H2 behaves almost the same as that of sample H1.
  • the signal read out by the anomalous Hall effect or magnetoresistive effect can be increased in the direction in which compressive strain is applied.
  • the magnitude of magnetization, the anomalous Hall effect, and the magnetoresistive effect can be controlled by applying compressive strain. This enables high-speed write and read operations using a magnetic memory element using antiferromagnetic material.
  • antiferromagnetic layer described in the first and second embodiments may be a single crystal film or a polycrystalline film.
  • free layer antiferromagnetic layer
  • a third embodiment of the present invention will be described with reference to FIGS. 16 to 19.
  • the third embodiment is directed to a magnetic memory element including a magnetoresistive element.
  • the magnetoresistive element 30 includes a free layer 32 whose magnetization is reversible, a non-magnetic layer 34 in contact with the free layer 32, and a magnetization in-plane or perpendicular to the non-magnetic layer 34. and a reference layer 36 whose direction is fixed.
  • the nonmagnetic layer 34 is made of an insulator (eg, MgO, AlOx, MgAl 2 O 4 ).
  • the free layer 32 and the reference layer 36 are both thin films made of the same antiferromagnetic metal as the antiferromagnetic layer 14 of FIG. 1, but the reference layer 36 has a larger coercive force than the free layer 32.
  • the free layer 32 preferably has the uniaxial strain (epitaxial strain or compressive strain) described in the first embodiment or the second embodiment.
  • the magnetoresistive element 30 functions as a magnetic tunnel junction (MTJ) element.
  • MTJ magnetic tunnel junction
  • Data “0” and “1” are assigned to the magnetoresistive element 30 depending on the resistance state. For example, when the free layer 32 and the reference layer 36 are made of Mn 3 Sn, as shown in FIG. When (parallel state), the magnetoresistive element 30 is in a low resistance state, and when the directions are opposite to each other (antiparallel state), the magnetoresistive element 30 is in a high resistance state. Parallel state data can be assigned as "0", and anti-parallel state data can be assigned as "1". In addition, experimentally, the magnetoresistive element 30 may be in a high resistance state when in the parallel state, and may be in a low resistance state when in the antiparallel state.
  • tunnel magnetoresistive effect of a ferromagnetic layer/nonmagnetic layer/ferromagnetic layer magnetoresistive element is proportional to the spin polarization of the ferromagnetic material.
  • TMR tunnel magnetoresistive effect
  • Mn 3 Sn which is an antiferromagnetic material, has a spin polarization rate that is three orders of magnitude smaller than that of iron (Fe), which is a ferromagnetic material.
  • the TMR rate (%) is ⁇ (R H - R L )/R H ⁇ 100( %).
  • a TMR rate of approximately 1% has been observed for the Mn 3 Sn/MgO/Mn 3 Sn multilayer, which is greater than the TMR rate observed for the Fe/MgO/Mn 3 Sn multilayer.
  • the magnetic memory element according to the third embodiment can function as a magnetic random access memory (MRAM) element.
  • MRAM magnetic random access memory
  • FIG. 18 shows the configuration of a magnetic memory element 200 of SOT-MRAM.
  • the magnetic memory element 200 includes a magnetoresistive element 210, a spin Hall layer 220, a first terminal 231, a second terminal 232, a third terminal 233, and transistors Tr1 and Tr2.
  • the spin Hall layer 220 is made of a nonmagnetic heavy metal (W, Ta, etc.) or a chalcogenide substance that exhibits the spin Hall effect.
  • the magnetoresistive element 210 includes a free layer 212 that is laminated on a spin Hall layer 220 and whose magnetization can be reversed, a nonmagnetic layer 214 that is laminated on the free layer 212, and a free layer 214 that is laminated on the nonmagnetic layer 214 and whose magnetization is reversible.
  • the reference layer 216 is fixed in the direction perpendicular to the plane. Free layer 212, nonmagnetic layer 214, and reference layer 216 are made of the same material as free layer 32, nonmagnetic layer 34, and reference layer 36 of FIG. 16, respectively.
  • the first terminal 231, the second terminal 232, and the third terminal 233 are made of metal.
  • a first terminal 231 is connected to the reference layer 216, a second terminal 232 is connected to one end of the spin hole layer 220, and a third terminal 233 is connected to the other end of the spin hole layer 220.
  • the first terminal 231 is connected to a ground line 240.
  • Ground line 240 is set to ground voltage. Note that the ground line 240 may be set to a reference voltage other than the ground voltage.
  • the transistors Tr1 and Tr2 are, for example, N-channel metal oxide semiconductor (NMOS) transistors.
  • the second terminal 232 is connected to the drain of the transistor Tr1, and the third terminal 233 is connected to the drain of the transistor Tr2.
  • the gates of transistors Tr1 and Tr2 are connected to word line WL.
  • the source of the transistor Tr1 is connected to the first bit line BL1, and the source of the transistor Tr2 is connected to the second bit line BL2.
  • the word line WL is set to a high level, transistors Tr1 and Tr2 are turned on, one bit line (second bit line BL2) is set to a high level, The other bit line (first bit line BL1) is left open.
  • a read current I flows from the high level second bit line BL2 to the third terminal 233, spin hole layer 220, free layer 212, nonmagnetic layer 214, reference layer 216, first terminal 231, and ground line 240. read flows.
  • the resistance state of the magnetoresistive element 210 that is, the stored data can be determined.
  • FIG. 19 shows the configuration of a magnetic memory element 300 of an MRAM (STT-MRAM) that uses spin transfer torque (STT) to reverse magnetization.
  • the magnetic memory element 300 includes a magnetoresistive element 310, a first terminal 321, a second terminal 322, and a transistor Tr.
  • the magnetoresistive element 310 includes a reference layer 316 whose magnetization is fixed perpendicular to the plane, a nonmagnetic layer 314 laminated on the reference layer 316, and a free layer laminated on the nonmagnetic layer 314 whose magnetization is reversible. 312.
  • Free layer 312, nonmagnetic layer 314, and reference layer 316 are made of the same material as free layer 32, nonmagnetic layer 34, and reference layer 36 of FIG. 16, respectively.
  • the first terminal 321 and the second terminal 322 are made of metal.
  • the free layer 312 is connected to a first terminal 321 and the reference layer 316 is connected to a second terminal 322.
  • the first terminal 321 is connected to the bit line BL, and the second terminal 322 is connected to the transistor Tr.
  • the transistor Tr is, for example, an NMOS transistor.
  • the second terminal 322 is connected to the drain of the transistor Tr, the source line SL is connected to the source, and the word line WL is connected to the gate.
  • the word line WL is set to a high level, the transistor Tr is turned on, and a write current I write in a direction perpendicular to the plane is caused to flow between the bit line BL and the source line SL.
  • the magnetization of the free layer 312 is reversed by the STT, and data can be written.
  • the data to be written can be changed depending on the direction of the write current I write .
  • the word line WL is set to a high level, the transistor Tr is turned on, and a read current I read is caused to flow between the bit line BL and the source line SL.
  • the resistance state of the magnetoresistive element 310 that is, the stored data can be determined.
  • FIGS. 16, 18, and 19 show examples in which the magnetoresistive elements 30, 210, and 310 are MTJ elements, they can also function as giant magnetoresistive (GMR) elements.
  • the nonmagnetic layers 34, 214, and 314 are made of metal (conductor).
  • the reference layer 216 in FIG. 18 and the reference layer 316 in FIG. may also be used as a magnetic layer.
  • FIG. 16 shows examples in which the magnetoresistive elements 30, 210, and 310 are MTJ elements, they can also function as giant magnetoresistive (GMR) elements.
  • the nonmagnetic layers 34, 214, and 314 are made of metal (conductor).
  • the reference layer 216 in FIG. 18 and the reference layer 316 in FIG. may also be used as a magnetic layer.
  • ferromagnetic layer made of a ferromagnetic material (for example, CoFeB) with a thickness of 2 nm or less is laminated on the antiferromagnetic layer as the free layer 212, and [antiferromagnetic layer/ferromagnetic layer]
  • a magnetoresistive element consisting of (free layer)/nonmagnetic layer/ferromagnetic layer (reference layer) may be employed.
  • This laminated structure may be turned upside down to adopt a magnetoresistive element consisting of ferromagnetic layer (reference layer)/non-magnetic layer/[ferromagnetic layer/antiferromagnetic layer (free layer)] as shown in FIG. .
  • a magnetic memory device may be configured in which a plurality of magnetic memory elements 200 are arranged in a matrix.
  • a magnetic memory device may be configured in which a plurality of magnetic memory elements 300 are arranged in a matrix.
  • a computer system or an information processing system may be configured including such a magnetic memory device.
  • Substrate 12 220 Spin Hall layer 14, 20 Antiferromagnetic layer 100, 200, 300 Magnetic memory element 16a, 16b, 18a, 18b Electrode 30, 210, 310 Magnetoresistive element 32, 212, 312 Free layer 34, 214, 314 Nonmagnetic layer 36, 216, 316 Reference layer

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PCT/JP2023/019977 2022-05-30 2023-05-29 磁気メモリ素子、情報処理システム、及び磁気メモリ素子の制御方法 Ceased WO2023234269A1 (ja)

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EP23816026.1A EP4535954A1 (en) 2022-05-30 2023-05-29 Magnetic memory element, information processing system, and mehod for controlling magnetic memory element
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