Giant spin-accumulation signal and pure spin-current-induced reversible magnetization switching

Because of the capability to switch the magnetization of a nanoscale magnet, the spin transfer effect is critical for the application of magnetic random access memory. For this purpose, it is important to enhance the spin current carried by the charge current. Calculations based on the diffusive spin-dependent transport equations reveal that the magnitude of spin current can be tuned by modifying the ferromagnetic layer and the spin relaxation process in the device. Increasing the ferromagnetic layer thickness is found to enhance both the spin current and the spin accumulation. On the other hand, a strong spin relaxation in the capping layer also increases the spin current but suppresses the spin accumulation. To demonstrate the theoretical results, nanopillar structures with the size of ∼100 nm are fabricated and the current-induced magnetization switching behaviors are experimentally studied. When the ferromagnetic layer thickness is increased from 3 nm to 20 nm, the critical switching current for the current-induced magnetization switching is significantly reduced, indicating the enhancement of the spin current. When the Au capping layer with a short spin-diffusion length replaces the Cu capping layer with a long spin-diffusion length, the reduction of the critical switching current is also observed.

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Magnetization switching of a perpendicular nanomagnet induced by vertical nonlocal injection of pure spin current

Scientific Reports ◽

10.1038/s41598-019-56082-x ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Hirofumi Suto ◽

Tazumi Nagasawa ◽

Taro Kanao ◽

Kenichiro Yamada ◽

Koichi Mizushima

Keyword(s):

Spin Injection ◽

Spin Current ◽

Pure Spin ◽

Spin Torque ◽

Device Structure ◽

Magnetization Switching ◽

Spintronic Devices ◽

Perpendicular Magnetization ◽

Vertical Injection ◽

Current Flows

AbstractInjection of pure spin current using a nonlocal geometry is a promising method for controlling magnetization in spintronic devices from the viewpoints of increasing freedom in device structure and avoiding problems related to charge current. Here, we report an experimental demonstration of magnetization switching of a perpendicular magnetic nanodot induced by vertical injection of pure spin current from a spin polarizer with perpendicular magnetization. In comparison with direct spin injection, the current amplitude required for magnetization switching is of the same order and shows smaller asymmetry between parallel-to-antiparallel and antiparallel-to-parallel switching. Simulation of spin accumulation reveals that, in the case of nonlocal spin injection, the spin torque is symmetric between the parallel and antiparallel configuration because current flows through only the spin polarizer, not the magnetic nanodot. This characteristic of nonlocal spin injection is the origin of the smaller asymmetry of the switching current and can be advantageous in spintronic applications.

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Spin accumulation and pure spin current in a three-terminal quantum dot ring with Rashba spin-orbit effect

Journal of Applied Physics ◽

10.1063/1.2973339 ◽

2008 ◽

Vol 104 (4) ◽

pp. 043707 ◽

Cited By ~ 12

Author(s):

Feng Chi ◽

Jun Zheng ◽

Lian-Liang Sun

Keyword(s):

Quantum Dot ◽

Spin Current ◽

Pure Spin ◽

Spin Accumulation ◽

Spin Orbit ◽

Rashba Spin

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Micromagnetics Simulation for Magnetization Switching of Permalloy Films with Pure Spin Current Injection

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2012.6481 ◽

2012 ◽

Vol 12 (11) ◽

pp. 8662-8665 ◽

Cited By ~ 3

Author(s):

Syuta Honda ◽

Hiroyoshi Itoh

Keyword(s):

Spin Current ◽

Current Injection ◽

Pure Spin ◽

Magnetization Switching

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PERFECT ALLOYS FOR SPIN HALL CURRENT-INDUCED MAGNETIZATION SWITCHING

SPIN ◽

10.1142/s2010324712500105 ◽

2012 ◽

Vol 02 (02) ◽

pp. 1250010 ◽

Cited By ~ 16

Author(s):

MARTIN GRADHAND ◽

DMITRY V. FEDOROV ◽

PETER ZAHN ◽

INGRID MERTIG ◽

YOSHICHIKA OTANI ◽

...

Keyword(s):

Hall Effect ◽

Noble Metals ◽

Spin Diffusion ◽

Spin Current ◽

Material Design ◽

Spin Hall Effect ◽

Pure Spin ◽

Magnetization Switching ◽

Hall Angle ◽

Electronic Measurement

We propose a device that allows for magnetization switching in nanomagnets by means of a pure spin current induced by the spin Hall effect. For this purpose we combine the ideas of magnetization switching of a ferromagnet by a spin current produced via the spin accumulation at a ferromagnet/nonmagnet interface with the electronic measurement of the direct spin Hall effect, and the theoretical material design to identify systems with a large spin Hall angle and an appropriate spin diffusion length. We will discuss the device design with respect to the size of the charge and spin currents. Based on ab initio calculations, we predict dilute alloys ideally suited for this application. Noble metals with single-sheeted Fermi surfaces, doped with either heavy impurities like Bi and Pb in Cu or Bi in Ag and light impurities like C and N in Au , seem to be the best candidates for a spin Hall angle larger than 5%.

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Pure spin-current-induced magnetization switching

10.1117/12.793903 ◽

2008 ◽

Author(s):

T. Yang ◽

T. Kimura ◽

J.-B. Laloë ◽

Y. Otani

Keyword(s):

Spin Current ◽

Pure Spin ◽

Magnetization Switching

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Enhanced spin accumulation in nano-pillar-based lateral spin valve using spin reservoir effect

Journal of Physics D Applied Physics ◽

10.1088/1361-6463/ac47bf ◽

2022 ◽

Author(s):

Xiaomin Cui ◽

Shaojie Hu ◽

Takashi Kimura

Keyword(s):

Spin Diffusion ◽

Spin Injection ◽

Spin Valve ◽

Spin Current ◽

Spin Valves ◽

Pure Spin ◽

Spin Accumulation ◽

Spintronic Devices ◽

High Bias ◽

Angle Deposition

Abstract Lateral spin valves are ideal nanostructures for investigating spin-transport physics phenomena and promoting the development of future spintronic devices owing to dissipation-less pure spin current. The magnitude of the spin accumulation signal is well understood as a barometer for characterizing spin current devices. Here, we develop a novel fabrication method for lateral spin valves based on ferromagnetic nanopillar structures using a multi-angle deposition technique. We demonstrate that the spin-accumulation signal is effectively enhanced by reducing the lateral dimension of the nonmagnetic spin channel. The obtained results can be quantitatively explained by the confinement of the spin reservoir by considering spin diffusion into the leads. The temperature dependence of the spin accumulation signal and the influence of the thermal spin injection under a high bias current are also discussed.

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Pure spin photocurrent in non-centrosymmetric crystals: bulk spin photovoltaic effect

Nature Communications ◽

10.1038/s41467-021-24541-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Haowei Xu ◽

Hua Wang ◽

Jian Zhou ◽

Ju Li

Keyword(s):

Mirror Symmetry ◽

Photovoltaic Effect ◽

Transition Metal Dichalcogenides ◽

Spin Current ◽

Pure Spin ◽

Light Illumination ◽

Metal Dichalcogenides ◽

Critical Components ◽

Topological Crystalline Insulator

AbstractSpin current generators are critical components for spintronics-based information processing. In this work, we theoretically and computationally investigate the bulk spin photovoltaic (BSPV) effect for creating DC spin current under light illumination. The only requirement for BSPV is inversion symmetry breaking, thus it applies to a broad range of materials and can be readily integrated with existing semiconductor technologies. The BSPV effect is a cousin of the bulk photovoltaic (BPV) effect, whereby a DC charge current is generated under light. Thanks to the different selection rules on spin and charge currents, a pure spin current can be realized if the system possesses mirror symmetry or inversion-mirror symmetry. The mechanism of BSPV and the role of the electronic relaxation time $$\tau$$ τ are also elucidated. We apply our theory to several distinct materials, including monolayer transition metal dichalcogenides, anti-ferromagnetic bilayer MnBi2Te4, and the surface of topological crystalline insulator cubic SnTe.

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