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

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.

Effects of FM/NM Interfaces on Spin Accumulation in Free Layer of Pseudo-Spin-Valve Structure

2007 ◽  
Vol 998 ◽  
Author(s):  
Jiuning Hu ◽  
Min Ren ◽  
Lei Zhang ◽  
Ning Deng ◽  
Hao Dong ◽  
...  
Keyword(s):  
Spin Diffusion ◽  
Spin Valve ◽  
Spin Current ◽  
Spin Accumulation ◽  
Free Layer ◽  
Fixed Layer ◽  
Spacer Layer ◽  
Polarization Factor ◽  
Valve Structure ◽  
Parallel Configuration

ABSTRACTThe ferromagnetic/nonmagnetic (FM/NM) interfacial effects on the spin accumulation in the free layer were studied in a pseudo-spin-valve structure (PSVs) consisting of two FM layers separated by a NM spacer layer. We developed a spin current model for the current-induced magnetic switching (CIMS) effect based on the spin diffusion equations and appropriate boundary conditions, and derived a new formula for the spin-dependent electrochemical potentials that are related to the spin-dependent density of states. The results indicate that the spin accumulation in the free layer mainly depends on the interfacial spin asymmetry coefficient Ξ?which originates from the spin-dependent interfacial conductance. In the parallel (anti-parallel) configuration of the magnetization direction for the free and fixed layer, the positive (negative) electron current (electrons from the free layer to the fixed layer and vice versa) drives the spin current polarization factor at the interface between the top electrode and the free layer to vary from Ξ? (-Ξ?) to 0, while at the interface between the free layer and the spacer layer the spin current polarization factor vary from Ξ? (0) to Ξ?/2, which means the total spin current polarization factor in the free layer varies from 0 (Ξ?) to Ξ?/2. These results show that the anti-parallel configuration has a less critical switching current than that of the parallel configuration. Thus, we can design PSVs with symmetrical critical current based on the model.

scholarly journals NONLOCAL ELECTRONIC SPIN DETECTION, SPIN ACCUMULATION AND THE SPIN HALL EFFECT

2009 ◽  
Vol 23 (11) ◽  
pp. 2413-2438 ◽  
Author(s):  
SERGIO O. VALENZUELA
Keyword(s):  
Hall Effect ◽  
Spin Diffusion ◽  
Spin Injection ◽  
Spin Hall Effect ◽  
Current Status ◽  
Pure Spin ◽  
Spin Accumulation ◽  
Spin Currents ◽  
Electrical Spin ◽  
Spin Detection

In recent years, electrical spin injection and detection has grown into a lively area of research in the field of spintronics. Spin injection into a paramagnetic material is usually achieved by means of a ferromagnetic source, whereas the induced spin accumulation or associated spin currents are detected by means of a second ferromagnet or the reciprocal spin Hall effect, respectively. This article reviews the current status of this subject, describing both recent progress and well-established results. The emphasis is on experimental techniques and accomplishments that brought about important advances in spin phenomena and possible technological applications. These advances include, amongst others, the characterization of spin diffusion and precession in a variety of materials, such as metals, semiconductors and graphene, the determination of the spin polarization of tunneling electrons as a function of the bias voltage, and the implementation of magnetization reversal in nanoscale ferromagnetic particles with pure spin currents.

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

2019 ◽  
Vol 9 (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.

scholarly journals Manipulation of spin currents in metallic systems

2011 ◽  
Vol 369 (1948) ◽  
pp. 3136-3149 ◽  
Author(s):  
Yoshichika Otani ◽  
Takashi Kimura
Keyword(s):  
Room Temperature ◽  
Spin Diffusion ◽  
Diffusion Processes ◽  
Spin Injection ◽  
Spin Current ◽  
Hybrid Structures ◽  
Pure Spin ◽  
Spin Currents ◽  
Magnetic Metal ◽  
Hall Effect Measurements

The transport properties of diffusive spin currents have been investigated in lateral ferromagnetic/non-magnetic metal hybrid structures. The spin diffusion processes were found to be strongly dependent on the magnitude of the spin resistances of connected materials. Efficient spin injection and detection are accomplished by optimizing the junction structures on the basis of the spin resistance circuitry. The magnetization switching of a nanoscale ferromagnetic particle and also room temperature spin Hall effect measurements were realized by using an efficient pure-spin-current injection.

Incoherent spin current

2017 ◽  
Author(s):  
K. Ando ◽  
E. Saitoh
Keyword(s):  
Diffusion Equation ◽  
Spin Density ◽  
Spin Diffusion ◽  
Spin Injection ◽  
Spin Current ◽  
Ferromagnetic Semiconductor ◽  
Electrochemical Potential ◽  
Semiconductor Interface ◽  
Interface Resistance ◽  
Inhomogeneous Spin

This chapter introduces the concept of incoherent spin current. A diffusive spin current can be driven by spatial inhomogeneous spin density. Such spin flow is formulated using the spin diffusion equation with spin-dependent electrochemical potential. The chapter also proposes a solution to the problem known as the conductivity mismatch problem of spin injection into a semiconductor. A way to overcome the problem is by using a ferromagnetic semiconductor as a spin source; another is to insert a spin-dependent interface resistance at a metal–semiconductor interface.

Effective modulation of spin accumulation using a ferromagnetic/nonmagnetic bilayer spin channel

2021 ◽  
Author(s):  
Taisei Ariki ◽  
Tatsuya Nomura ◽  
Kohei Ohnishi ◽  
Takashi Kimura
Keyword(s):  
Spin Injection ◽  
Spin Valve ◽  
Transverse Spin ◽  
Spin Accumulation ◽  
Spin Channel ◽  
Relative Angle ◽  
Channel Layer ◽  
Spin Polarized ◽  
Resistance Model ◽  
Large Spin

Abstract A lateral spin valve consisting of highly spin-polarized CoFeAl electrodes with a CoFeAl/Cu bilayer spin channel has been developed. Despite a large spin absorption into the CoFeAl capping channel layer, an efficient spin injection and detection using the CoFeAl electrodes enable us to observe a clear spin valve signal. We demonstrate that the nonlocal spin accumulation signal is significantly modulated depending on the relative angle of the magnetizations between the spin injector and absorber. The observed modulation phenomena is explained by the longitudinal and transverse spin absorption effects into the CoFeAl channel layer with the spin resistance model.

Manipulating Spin Current in the Magnetic Nanopillar

2007 ◽  
Vol 7 (1) ◽  
pp. 259-264 ◽  
Author(s):  
T. Yang ◽  
A. Hirohata ◽  
T. Kimura ◽  
Y. Otani
Keyword(s):  
Layer Thickness ◽  
Spin Relaxation ◽  
Spin Diffusion ◽  
Diffusion Length ◽  
Ferromagnetic Layer ◽  
Spin Current ◽  
Spin Accumulation ◽  
Magnetization Switching ◽  
Capping Layer ◽  
Spin Diffusion Length

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.

Spin Diffusion in the Finite Magnetic Heterojunction

2017 ◽  
Vol 727 ◽  
pp. 410-414
Author(s):  
Yi Lin Mi
Keyword(s):  
Spin Polarization ◽  
Organic Semiconductors ◽  
Spin Diffusion ◽  
Spin Injection ◽  
Great Influence ◽  
Injection Efficiency ◽  
Spintronic Devices ◽  
Ferromagnetic Electrodes ◽  
Spin Polarons ◽  
The Difference

Spin diffusion in the finite magnetic heterojunction was explored considering the spin dependent conductivity. In organic semiconductor spintronic devices, the up-spin and down-spin polarons have different density once spin injection happens from ferromagnetic electrodes into organic semiconductors. The difference results in the spin dependent conductivity. The calculations show that the spin injection efficiency is dependent on the spin dependent conductivity and the size of the layers. The spin dependent conductivity has great influence on the spin injection efficiency in the finite magnetic heterojunction, when the spin polarization of the organic semiconductors is moderate.

scholarly journals Electric Field Modulation of Spin Accumulation in Nb-doped SrTiO3 with Ni/AlOx Spin Injection Contacts

SPIN ◽  
2018 ◽  
Vol 08 (01) ◽  
pp. 1840004 ◽  
Author(s):  
A. Das ◽  
S. T. Jousma ◽  
T. Banerjee
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Spin Injection ◽  
Complex Oxide ◽  
Spin Accumulation ◽  
Spin Orbit ◽  
Strong Response ◽  
Spintronic Devices ◽  
Spin Lifetime ◽  
Field Modulation

We demonstrate an electric field control of spin lifetime at room temperature, across a semiconducting interface of Nb:STO using Ni/AlOx as spin injection contacts. We achieve this by a careful tailoring of the potential landscape in Nb:STO, driven by the strong response of the intrinsically large dielectric permittivity in STO to electric fields. The built-in electric field at the Schottky interface with Nb:STO tunes the intrinsic Rashba spin–orbit fields leading to a bias dependence of the spin lifetime in Nb:STO. Such an electric field driven modulation of spin accumulation has not been reported earlier using conventional semiconductors. This not only underpins the necessity of a careful design of the spin injection contacts but also establishes the importance of Nb:STO as a rich platform for exploring spin–orbit driven phenomena in complex oxide based spintronic devices.

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