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WO2024095960A1 - Élément de mémoire magnétique et dispositif de mémoire magnétique - Google Patents

Élément de mémoire magnétique et dispositif de mémoire magnétique Download PDF

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Publication number
WO2024095960A1
WO2024095960A1 PCT/JP2023/039096 JP2023039096W WO2024095960A1 WO 2024095960 A1 WO2024095960 A1 WO 2024095960A1 JP 2023039096 W JP2023039096 W JP 2023039096W WO 2024095960 A1 WO2024095960 A1 WO 2024095960A1
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layer
topological
magnetic
ferrimagnetic
magnetic memory
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Japanese (ja)
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知 中▲辻▼
明人 酒井
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University of Tokyo NUC
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University of Tokyo NUC
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    • 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
    • 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
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N52/00—Hall-effect devices

Definitions

  • the present invention relates to a magnetic memory element and a magnetic memory device.
  • MRAM magnetic random access memory
  • SRAM static random access memory
  • STT-MRAM spin transfer torque (STT) to reverse the magnetization of a ferromagnetic material
  • SOT-MRAM spin orbit torque (SOT) to reverse the magnetization of a ferromagnetic material
  • MRAM uses ferromagnetic materials, and the magnetization reversal speed is limited to about 1 nanosecond, so it has not yet become an alternative to SRAM.
  • ferromagnetic materials are vulnerable to disturbances from external magnetic fields.
  • the present invention was made in consideration of the above problems, and aims to provide a magnetic memory element and a magnetic memory device that use a ferrimagnetic material to improve resistance to disturbances from external magnetic fields and achieve high-speed processing.
  • the magnetic memory element of one embodiment of the present invention comprises a magnetoresistance element having a free layer in which the magnetic order is reversible, a fixed layer in which the magnetic order is fixed, and a non-magnetic layer provided between the free layer and the fixed layer, and at least one of the free layer and the fixed layer is made of a topological ferrimagnet that exhibits the anomalous Hall effect and the anomalous Nernst effect.
  • a magnetic memory device includes a plurality of magnetic memory elements, each of which is defined as the magnetic memory element described above.
  • a magnetic memory element comprises a ferrimagnetic layer made of a topological ferrimagnet that exhibits the anomalous Hall effect and the anomalous Nernst effect, and a spin Hall layer in contact with the ferrimagnetic layer, made of a material that exhibits the spin Hall effect, in which a spin current is generated perpendicular to the plane when a write current flows in the in-plane direction.
  • the magnetic order of the topological ferrimagnet can be reversed by the spin-orbit torque generated by the spin current.
  • Another aspect of the present invention is a magnetic memory device that includes a plurality of magnetic memory elements, each of which is defined as the magnetic memory element described above.
  • the present invention by using a topological ferrimagnetic material that exhibits the anomalous Hall effect and the anomalous Nernst effect in a magnetic memory element, it is possible to increase the tolerance to disturbances caused by external magnetic fields and achieve high-speed processing.
  • 1 is a graph showing the relationship between magnetization and transverse thermoelectric coefficient of various magnetic materials.
  • 1 is a graph showing the magnetic field dependence of Hall resistivity of Gd 2 Co 7 and Ho 1.2 Gd 0.8 Co 7 .
  • 1 is a graph showing the temperature dependence of Hall resistivity of Gd 2 Co 7 and Ho 1.2 Gd 0.8 Co 7 .
  • 1 is a graph showing the magnetic field dependence of Hall resistivity of GdCo5.
  • 1 is a graph showing the temperature dependence of Hall resistivity of GdCo5.
  • 3 is a cross-sectional view of a magnetoresistive element of the first memory structure according to the first embodiment.
  • FIG. 4 is a cross-sectional view of a magnetoresistive element of a second memory structure according to the first embodiment.
  • FIG. 4 is a cross-sectional view of a magnetoresistive element of a third memory structure according to the first embodiment.
  • FIG. 1 is a graph showing the relationship between saturation magnetization and uniaxial magnetic anisotropy energy of various magnetic materials.
  • FIG. 1 is a schematic diagram showing the configuration of a magnetic memory element of an SOT-MRAM.
  • FIG. 1 is a schematic diagram showing the configuration of a magnetic memory element of an STT-MRAM.
  • FIG. 1 is a schematic diagram showing the configuration of a magnetic memory element using an all-optical data writing method.
  • FIG. 11 is a schematic diagram showing the configuration of a magnetic memory element according to a second embodiment.
  • ferrimagnetic materials which have smaller magnetization than ferromagnetic materials, in order to realize a nonvolatile magnetic memory device that is resistant to disturbances from external magnetic fields and can operate at high speeds.
  • Ferrimagnetic materials have a small net magnetization because two different types of magnetic ions are antiferromagnetically coupled and cancel each other out with their sublattice magnetizations.
  • the sum of the two sublattice magnetizations can be made zero by changing the temperature or the concentrations of the two types of magnetic ions. Such a temperature or concentration is called the magnetization compensation point.
  • the magnetization compensation point By tuning the temperature or composition, the net magnetization of a ferrimagnetic material can be made almost zero, thereby increasing its resistance to external magnetic fields.
  • the angular momentum compensation point where the angular momenta of the two sublattices cancel each other out, resulting in the net angular momentum disappearing.
  • the material has a finite magnetization at the angular momentum compensation point, and the speed of magnetic dynamics such as precession of the magnetic moment and domain wall velocity is maximized, enabling high-speed magnetization reversal.
  • a magnetic response is required whose magnitude can be clearly detected, even though the magnetization is minute.
  • This embodiment focuses on a topological ferrimagnet, which, due to the topology of its electronic state, can provide a response far greater than would be expected from the magnitude of the magnetization.
  • topological ferrimagnets examples include alloys (R-TM) consisting of rare earth elements (R) and 3d transition metals (TM), such as Mn 5 Ge 2 , Mn 3 Ga, Mn 3 SnN, and Mn 4 N.
  • TM in R-TM examples include cobalt (Co) and iron (Fe).
  • the ratio (x/y) of R to TM is preferably within the range of 0.2 to 0.5. Note that R in R-TM may be a combination of two rare earth elements.
  • the topological ferrimagnetic material of this embodiment has the property of exhibiting the anomalous Nernst effect and the anomalous Hall effect despite minute magnetization.
  • Figure 1 shows the relationship between ⁇ 0 M ( ⁇ 0 is vacuum permeability, M is magnetization) and absolute value of transverse thermoelectric coefficient ⁇ ij for various magnetic materials at temperatures T>200K.
  • Figure 1 shows that
  • GdCo 5 has
  • Gd 2 Co 7 has
  • FIG. 2A shows the magnetic field dependence of the Hall resistivity ⁇ yx of Gd 2 Co 7 and Ho 1.2 Gd 0.8 Co 7 at 300 K (room temperature) when a magnetic field B parallel to the c-axis is applied.
  • FIG. 2B shows the temperature dependence of the Hall resistivity ⁇ yx of Gd 2 Co 7 and Ho 1.2 Gd 0.8 Co 7 when a magnetic field B of 1 T is applied parallel to the c-axis. From FIG. 2A and FIG. 2B, it can be seen that Gd 2 Co 7 and Ho 1.2 Gd 0.8 Co 7 show a large anomalous Hall effect. Also, from FIG.
  • FIG. 2C shows the magnetic field dependence of the Hall resistivity ⁇ yx at 100K, 200K, and 300K in GdCo 5 when a current I parallel to [2-1-10] is passed under a magnetic field B parallel to [0001].
  • FIG. 2D shows the temperature dependence of the Hall resistivity ⁇ yx in GdCo 5 when a current I parallel to [2-1-10] is passed under a magnetic field B of 2T parallel to [0001]. From FIG. 2C and FIG. 2D, it can be seen that the anomalous Hall effect is also manifested in GdCo 5. Also, from FIG. 2C, it can be seen that the coercive force appears at 200K or less, and the coercive force increases as the temperature decreases. Furthermore, from FIG. 2D, it can be seen that the magnitude of the Hall resistivity ⁇ yx increases monotonically with increasing temperature.
  • topological ferrimagnets exhibit large anomalous Nernst effect and large anomalous Hall effect despite minute magnetization originates from their crystal structure and band structure.
  • R2Co7 and RCo5 have rhombohedral or hexagonal crystal structures.
  • topological ferrimagnets have a topological band structure near the Fermi surface.
  • R2Co7 and RCo5 have flat bands near the Fermi surface, and the energy does not change even if the momentum changes. This suggests that the 4f electrons of R or the 3d electrons of Co are localized in real space.
  • the first embodiment will be directed to a magnetic memory element that uses the magnetoresistance effect to read data
  • the second embodiment will be directed to a magnetic memory element that uses the anomalous Hall effect to read data.
  • a first embodiment of the present invention will be described with reference to Figures 3A to 7.
  • the first embodiment is directed to three types of magnetic memory element structures (first to third memory structures).
  • FIG. 3A shows a cross-sectional view of a magnetoresistance element 100 of the first memory structure.
  • the magnetoresistance element 100 includes a free layer 112 in which the magnetic order is reversible, a nonmagnetic layer 114, and a fixed layer 116 in which the magnetic order is fixed, and the nonmagnetic layer 114 is provided between the free layer 112 and the fixed layer 116.
  • the nonmagnetic layer 114 is made of an insulator such as MgO, Al 2 O 3 , HfO, etc.
  • the free layer 112 includes a ferrimagnetic layer 1121 made of a topological ferrimagnetic material, and a first ferromagnetic layer 1123 made of a ferromagnetic material, sandwiched between the nonmagnetic layer 114 and the ferrimagnetic layer 1121, and having a thickness of 1 nm or less (several atomic layers).
  • the topological ferrimagnet of the ferrimagnetic layer 1121 is an alloy of a rare earth element and a 3d transition metal, and is preferably a ferrimagnet at the angular momentum compensation point.
  • Examples of the ferromagnetic material of the first ferromagnetic layer 1123 include CoFeB and CoFe.
  • the fixed layer 116 has an artificial antiferromagnetic layer 118, a bridge layer 1163 made of a metal such as tantalum (Ta) stacked on the artificial antiferromagnetic layer 118, and a second ferromagnetic layer 1161 stacked on the bridge layer 1163 and in contact with the nonmagnetic layer 114.
  • a bridge layer 1163 made of a metal such as tantalum (Ta) stacked on the artificial antiferromagnetic layer 118
  • a second ferromagnetic layer 1161 stacked on the bridge layer 1163 and in contact with the nonmagnetic layer 114.
  • the second ferromagnetic layer 1161 is made of the same ferromagnetic material as the first ferromagnetic layer 1123.
  • the laminated structure of the second ferromagnetic layer 1161/nonmagnetic layer 114/first ferromagnetic layer 1123 is preferably CoFe/MgO/CoFe or CoFeB/MgO/CoFeB.
  • MTJ magnetic tunnel junction
  • TMR tunnel magnetoresistance
  • an MTJ element with a CoFeB/MgO/CoFeB structure can achieve a TMR ratio of 200% or more at room temperature.
  • the artificial antiferromagnetic layer 118 has a first multilayer film 1165, a spacer layer 1167 made of a metal such as ruthenium (Ru), and a second multilayer film 1169, and the spacer layer 1167 is sandwiched between the first multilayer film 1165 and the second multilayer film 1169.
  • the first multilayer film 1165 is a multilayer film (Co/Pt) n in which a Co layer and a Pt layer are alternately stacked multiple times (n times)
  • the second multilayer film 1169 is a multilayer film (Co/Pt) m in which a Co layer and a Pt layer are alternately stacked multiple times (m times).
  • Such a Co/Pt multilayer film exhibits perpendicular magnetization because magnetic anisotropy appears in the perpendicular direction at the interface between Co/Pt.
  • the second ferromagnetic layer 1161 is ferromagnetically coupled to the first multilayer film 1165 with perpendicular magnetization via the bridge layer 1163, thereby increasing the coercive force of the second ferromagnetic layer 1161.
  • the first multilayer film 1165 is antiparallel coupled to the second multilayer film 1169 via the spacer layer 1167, thereby preventing leakage of the magnetic field from the fixed layer 116 to the free layer 112.
  • FIG. 3B shows a cross-sectional view of the magnetoresistance element 102 of the second memory structure.
  • the magnetoresistance element 102 comprises a free layer 122 in which the magnetic order is reversible, a nonmagnetic layer 124, and a fixed layer 126 in which the magnetic order is fixed, and the nonmagnetic layer 124 is provided between the free layer 122 and the fixed layer 126.
  • the free layer 122 has a first ferromagnetic layer 1223 laminated on the nonmagnetic layer 124, and a first ferrimagnetic layer 1221 laminated on the first ferromagnetic layer 1223.
  • the fixed layer 126 has a second ferrimagnetic layer 1263 made of a topological ferrimagnetic material, and a second ferromagnetic layer 1261 laminated on the second ferrimagnetic layer 1263 and in contact with the nonmagnetic layer 124.
  • the fixed layer 126 of the magnetoresistance element 102 has a simpler laminate structure than the fixed layer 116 having the artificial antiferromagnetic layer 118 shown in FIG. 3A.
  • the first ferromagnetic layer 1221, the first ferromagnetic layer 1223, the nonmagnetic layer 124, and the second ferromagnetic layer 1261 of the magnetoresistance element 102 shown in FIG. 3B have the same configuration as the ferrimagnetic layer 1121, the first ferromagnetic layer 1123, the nonmagnetic layer 114, and the second ferromagnetic layer 1161 of the magnetoresistance element 100 shown in FIG. 3A, respectively, and therefore their description will be omitted.
  • the topological ferrimagnetic material constituting the second ferrimagnetic layer 1263 is preferably a ferrimagnetic material in the vicinity of the magnetization compensation point.
  • a magnetic hardness parameter ⁇ defined by the formula (1) is introduced.
  • K u represents uniaxial magnetic anisotropy energy
  • ⁇ 0 represents vacuum permeability
  • M s represents saturation magnetization.
  • FIG. 4 shows the relationship between ⁇ 0 M s and K u for various magnetic materials.
  • ⁇ 0.1 is a soft magnetic material
  • 0.1 ⁇ 1 is a semi-hard magnetic material
  • 1 ⁇ 10 is a hard magnetic material
  • ⁇ 10 is an ultra-hard magnetic material.
  • topological ferrimagnetic materials such as YCo 5 , GdCo 5 , Y 2 Co 7 , Gd 2 Co 7 , and Ho 1.2 Gd 0.8 Co 7 are magnetically very hard magnetic materials with ⁇ of 1 or more.
  • GdCo 5 , Gd 2 Co 7 , and Ho 1.2 Gd 0.8 Co 7 are magnetically harder than Sm—Co and Nd—Fe—B permanent magnets.
  • a topological ferrimagnetic material with ⁇ 1 is used for the second ferrimagnetic layer 1263, it is possible to ensure sufficiently high thermal stability even if the volume is small.
  • Ms is infinitely close to zero, so as is clear from formula (1), even if Ku is small, the value of ⁇ is large. This allows a large coercive force to be obtained.
  • a thin film of a topological ferrimagnetic material made of a rare earth element and a 3d transition metal exhibits bulk perpendicular magnetic anisotropy, so that a pinned layer 126 with perpendicular magnetization can be realized.
  • a topological ferrimagnetic material at the angular momentum compensation point is used for the first ferrimagnetic layer 1221 of the free layer 122, and a topological ferrimagnetic material with ⁇ 1 near the magnetization compensation point is used for the second ferrimagnetic layer 1263 of the fixed layer 126.
  • a topological ferrimagnetic material made of a rare earth element and a 3d transition metal has different magnetization compensation points and angular momentum compensation points, and the angular momentum compensation point exists near the magnetization compensation point.
  • the topological ferrimagnetic material of the first ferrimagnetic layer 1221 and the topological ferrimagnetic material of the second ferrimagnetic layer 1263 have slightly different compositions (ratio of rare earth element to 3d transition metal), the composition can be tuned by adjusting the concentration of the magnetic ions that make up the topological ferrimagnetic material.
  • the free layer 122 of the magnetoresistance element 102 in FIG. 3B may be provided with only the first ferromagnetic layer 1223 having an appropriate thickness, without providing the first ferrimagnetic layer 1221.
  • FIG. 3C shows a cross-sectional view of the magnetoresistance element 104 of the third memory structure.
  • the magnetoresistance element 104 comprises a free layer 132 in which the magnetic order is reversible, a nonmagnetic layer 134, and a fixed layer 136 in which the magnetic order is fixed, and the nonmagnetic layer 134 is provided between the free layer 132 and the fixed layer 136.
  • Nonmagnetic layer 134 is made of the same material (e.g., MgO) as nonmagnetic layer 114 in FIG. 3A and nonmagnetic layer 124 in FIG. 3B.
  • the free layer 132 is made of a topological ferrimagnet at the angular momentum compensation point
  • the fixed layer 136 is made of a topological ferrimagnet with ⁇ 1 near the magnetization compensation point.
  • These topological ferrimagnets are alloys made of rare earth elements and 3d transition metals.
  • the concentration of the rare earth elements increases as they move away from the nonmagnetic layer 134 in the perpendicular direction
  • the concentration of the 3d transition metal increases as they approach the nonmagnetic layer 134 in the perpendicular direction.
  • the amount of rare earth elements can be adjusted using a shutter.
  • the free layer 132 of the magnetoresistance element 104 in FIG. 3C does not necessarily have to include a topological ferrimagnetic material, and may be made of only a ferromagnetic material such as CoFe or CoFeB.
  • the magnetoresistance elements 100, 102, and 104 shown in Figures 3A to 3C, respectively, can be applied to various magnetic memory elements and magnetic memory devices that use different data writing methods.
  • magnetic memory elements and magnetic memory devices that use data writing methods using spin-orbit torque (SOT), spin-transfer torque (STT), and an all-optical technique, respectively, will be described.
  • FIG. 5 shows the configuration of a magnetic memory element 200 of an SOT-MRAM in which the magnetic order (magnetization) is reversed by SOT.
  • the magnetic memory element 200 includes a magnetoresistance 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 material that exhibits the spin Hall effect (spin Hall material).
  • spin Hall materials include non-magnetic heavy metals such as tantalum (Ta), tungsten (W), and platinum (Pt), or chalcogenide materials such as topological insulators.
  • the magnetoresistance element 210 is stacked on the spin Hall layer 220 and includes a free layer 212 in which the magnetic order in the perpendicular direction is reversible, a non-magnetic layer 214 stacked on the free layer 212, and a fixed layer 216 stacked on the non-magnetic layer 214 and in which the magnetic order is fixed in the perpendicular direction.
  • the magnetoresistance element 210 may have any of the configurations of the magnetoresistance elements 100, 102, and 104 shown in Figures 3A to 3C.
  • the first terminal 231, the second terminal 232, and the third terminal 233 are made of metal.
  • the first terminal 231 is connected to the fixed layer 216, the second terminal 232 is connected to one end of the spin Hall layer 220, and the third terminal 233 is connected to the other end of the spin Hall layer 220.
  • the first terminal 231 is connected to the ground line 240.
  • the ground line 240 is set to the ground voltage.
  • the ground line 240 may be set to a reference voltage other than the ground voltage.
  • Transistors Tr1 and Tr2 are, for example, N-channel metal oxide semiconductor (NMOS) transistors.
  • the second terminal 232 is connected to the drain of transistor Tr1, and the third terminal 233 is connected to the drain of transistor Tr2.
  • the gates of transistors Tr1 and Tr2 are connected to the word line WL.
  • the source of transistor Tr1 is connected to the first bit line BL1, and the source of transistor Tr2 is connected to the second bit line BL2.
  • the word line WL is set to a high level to turn on the transistors Tr1 and Tr2, and one of the first bit line BL1 and the second bit line BL2 is set to a high level, and the other is set to a low level.
  • a write current I write (pulse current) flows in the in-plane direction of the spin Hall layer 220 between the first bit line BL1 and the second bit line BL2, generating a spin current in the perpendicular direction, and the magnetic order of the free layer 212 is reversed by the SOT, allowing data to be written.
  • the data to be written can be changed depending on the direction of the write current I write .
  • the pulse width of the write current I write is 20 ps to 50 ps.
  • the word line WL is set to a high level to turn on the transistors Tr1 and Tr2, one bit line (second bit line BL2) is set to a high level, and the other bit line (first bit line BL1) is opened.
  • a read current I read flows from the high-level second bit line BL2 to the third terminal 233, the spin Hall layer 220, the free layer 212, the nonmagnetic layer 214, the fixed layer 216, the first terminal 231, and the ground line 240.
  • the resistance state of the magnetoresistance element 210 i.e., the stored data, can be determined.
  • a magnetic memory device can be constructed by arranging multiple magnetic memory elements 200 in a matrix.
  • FIG. 6 shows the configuration of a magnetic memory element 300 of an STT-MRAM that uses STT to reverse the magnetic order (magnetization).
  • the magnetic memory element 300 includes a magnetoresistance element 310, a first terminal 321, a second terminal 322, and a transistor Tr.
  • the magnetoresistance element 310 includes a fixed layer 316 whose magnetic order is fixed in the perpendicular direction, a non-magnetic layer 314 laminated on the fixed layer 316, and a free layer 312 laminated on the non-magnetic layer 314, whose magnetic order in the perpendicular direction can be reversed.
  • the magnetoresistance element 310 may have any of the configurations of the magnetoresistance elements 100, 102, and 104 shown in Figures 3A to 3C.
  • the first terminal 321 and the second terminal 322 are made of metal.
  • the free layer 312 is connected to the first terminal 321, and the fixed layer 316 is connected to the 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 drain of the transistor Tr is connected to the second terminal 322, the source is connected to the source line SL, and the gate is connected to the word line WL.
  • the word line WL is set to a high level to turn on the transistor Tr, and a write current I write is passed between the bit line BL and the source line SL in the perpendicular direction. This causes the magnetic order of the free layer 312 to be reversed by the STT, allowing data to be written.
  • the data to be written can be changed by changing the direction of the write current I write .
  • the word line WL is set to a high level to turn on the transistor Tr, and a read current Iread is passed between the bit line BL and the source line SL.
  • the resistance state of the magnetoresistance element 310 i.e., the stored data, can be determined.
  • a magnetic memory device can be constructed by arranging multiple magnetic memory elements 300 in a matrix.
  • the magnetic memory element 400 shown in FIG. 7 includes a magnetoresistance element 410 and a cap layer 420 laminated on the magnetoresistance element 410.
  • the magnetoresistance element 410 includes a free layer 412 in which the magnetic order (magnetization) is reversible, a fixed layer 416 in which the magnetic order is fixed in the perpendicular direction, and a nonmagnetic layer 414 provided between the free layer 412 and the fixed layer 416.
  • the cap layer 420 is laminated on the free layer 412.
  • the cap layer 420 is made of an insulator such as Al 2 O 3 , MgO, etc.
  • the magnetoresistance element 410 may have any of the configurations of the magnetoresistance elements 100, 102, and 104 shown in FIGS.
  • the free layer 412 having a ferrimagnetic layer is irradiated with a pulse amplitude modulated femtosecond laser by the light irradiating unit 430.
  • the light irradiating unit 430 includes a light emitting unit 432 and a lens 434.
  • the light emitting unit 432 emits an ultrashort pulse laser PL with a pulse width of about 100 fs.
  • the pulse laser PL emitted from the light emitting unit 432 is focused in the free layer 412 by the lens 434.
  • the magnetic order of the topological ferrimagnetic material in the free layer 412 is reversed when light with an intensity equal to or greater than the threshold is irradiated, and no reversal of the magnetic order occurs when light with an intensity less than the threshold is irradiated.
  • the all-optical data writing method can reverse the magnetic order using the heat of light without the intervention of a current.
  • the magnetic order of a topological ferrimagnet can be reversed in a short time of about 10 ps.
  • the magnetoresistance element of FIG. 3A or FIG. 3B when the magnetic order of the ferrimagnetic layer is reversed, the magnetic order of the ferromagnetic layer closest to the ferrimagnetic layer is also reversed.
  • a magnetic memory device can be constructed by arranging multiple magnetic memory elements 400.
  • magnetoresistance elements 210, 310, and 410 are shown as MTJ elements in the examples shown in Figures 5 to 7, they can also function as giant magnetoresistance (GMR) elements.
  • the nonmagnetic layers 214, 314, and 414 are made of metal (conductor).
  • the topological ferrimagnet can exhibit a large anomalous Hall effect. Therefore, in the second embodiment, a magnetic memory element that reads data using the anomalous Hall effect will be described.
  • FIG. 8 shows the configuration of a magnetic memory element 500 with a Hall bar structure according to the second embodiment.
  • the magnetic memory element 500 includes a ferrimagnetic layer 510 and a spin Hall layer 520 in contact with the ferrimagnetic layer 510.
  • the ferrimagnetic layer 510 is made of a topological ferrimagnetic material, similar to the ferrimagnetic layer 1121, the first ferrimagnetic layer 1221, and the free layer 132 shown in FIGS. 3A to 3C.
  • the spin Hall layer 520 is made of a material that exhibits the spin Hall effect (for example, a nonmagnetic heavy metal such as Ta, W, or Pt, or a chalcogenide material such as a topological insulator).
  • Electrodes 552 and 554 made of Au/Ti are arranged at both ends in the longitudinal direction (x direction) of the magnetic memory element 500, and electrodes 562 and 564 made of Au/Ti are arranged in the lateral direction (y direction).
  • a write current I write or a read current I read flows between the electrodes 552 and 554, and a Hall voltage V H is detected between the electrodes 562 and 564.
  • a write current I write pulse current
  • a spin current in the perpendicular direction (z direction) due to the spin Hall effect
  • the SOT acts on the magnetic order (magnetization) of the ferrimagnetic layer 510, reversing the magnetic order.
  • Hx weak bias magnetic field
  • the direction of the magnetic order of the ferrimagnetic layer 510 can be controlled by the direction of the write current I write .
  • the magnetic order is reversed from the +z direction ("1") to the -z direction ("0")
  • the magnetic order is reversed from the -z direction ("0") to the +z direction ("1").
  • a read current I read (DC) is passed through the ferrimagnetic layer 510 in the x direction.
  • the sign of the Hall voltage V H is determined by the z-direction component of the magnetic order of the ferrimagnetic layer 510. For example, when the magnetic order of the ferrimagnetic layer 510 faces the +z direction, it corresponds to "1", and when it faces the -z direction, it corresponds to "0". In this way, the information stored depending on the direction of the magnetic order of the ferrimagnetic layer 510 can be read as a Hall voltage V H by passing a read current I read .
  • the magnetic memory element 500 of the second embodiment does not require a fixed layer and a nonmagnetic layer in contact with the fixed layer, simplifying the structure of the element and enabling miniaturization.

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Abstract

La présente invention concerne un élément de mémoire magnétique qui comprend : une couche libre (122) dans laquelle un ordre magnétique peut être inversé ; une couche fixe (126) dans laquelle un ordre magnétique est fixé ; et une couche non magnétique (124) disposée entre la couche libre (122) et la couche fixe (126). La couche libre (122) comprend une première couche ferromagnétique (1223) sur la couche non magnétique (124) et une première couche ferrimagnétique (1221) sur la première couche ferromagnétique (1223). La couche fixe (126) comprend une seconde couche ferrimagnétique (1263) et une seconde couche ferromagnétique (1261) sur la seconde couche ferrimagnétique (1263). La première couche ferrimagnétique (1221) est composée d'un ferriaimant topologique à un point de compensation de moment cinétique. La seconde couche ferrimagnétique (1263) est composée d'un ferriaimant topologique présentant un paramètre de dureté magnétique d'un ou plus. Le ferriaimant topologique est un ferriaimant qui présente un effet Hall anormal et un effet Nernst anormal.
PCT/JP2023/039096 2022-10-31 2023-10-30 Élément de mémoire magnétique et dispositif de mémoire magnétique Ceased WO2024095960A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009514193A (ja) * 2005-08-23 2009-04-02 グランディス インコーポレイテッド フェリ磁性体を用いるスピン遷移スイッチング磁気素子およびこの磁気素子を用いる磁気メモリ
WO2011033873A1 (fr) * 2009-09-17 2011-03-24 富士電機ホールディングス株式会社 Élément magnéto-résistif et dispositif semi-conducteur de mémoire non volatile utilisant celui-ci
WO2015072856A2 (fr) * 2013-11-14 2015-05-21 Stichting Katholieke Universiteit Nijmegen Dispositif magnéto-optique
WO2021240796A1 (fr) * 2020-05-29 2021-12-02 Tdk株式会社 Film magnétique, élément magnétorésistif et procédé de production de film magnétique

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009514193A (ja) * 2005-08-23 2009-04-02 グランディス インコーポレイテッド フェリ磁性体を用いるスピン遷移スイッチング磁気素子およびこの磁気素子を用いる磁気メモリ
WO2011033873A1 (fr) * 2009-09-17 2011-03-24 富士電機ホールディングス株式会社 Élément magnéto-résistif et dispositif semi-conducteur de mémoire non volatile utilisant celui-ci
WO2015072856A2 (fr) * 2013-11-14 2015-05-21 Stichting Katholieke Universiteit Nijmegen Dispositif magnéto-optique
WO2021240796A1 (fr) * 2020-05-29 2021-12-02 Tdk株式会社 Film magnétique, élément magnétorésistif et procédé de production de film magnétique

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