Robust spin-current injection in lateral spin valves with two-terminal Co2FeSi spin injectors

S Oki,K Hamaya,T Kanashima,H Itoh,S Honda,T Kurokawa,S Yamada

doi:10.1063/1.4972852

S Oki, K Hamaya + Show 5 more

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https://doi.org/10.1063/1.4972852

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Abstract

We demonstrate generation and detection of pure spin currents by combining a two-terminal spin-injection technique and Co2FeSi (CFS) spin injectors in lateral spin valves (LSVs). We find that the two-terminal spin injection with CFS has the robust dependence of the nonlocal spin signals on the applied bias currents, markedly superior to the four-terminal spin injection with permalloy reported previously. In our LSVs, since the spin transfer torque from one CFS injector to another CFS one is large, the nonlocal magnetoresistance with respect to applied magnetic fields shows large asymmetry in high bias-current conditions. For utilizing multi-terminal spin injection with CFS as a method for magnetization reversals, the terminal arrangement of CFS spin injectors should be taken into account.

Highlights

It is said that this degradation originates from the decrease in the spin diffusion length of the used N arising from the Joule heating of F materials with relatively high resistivity compared with N
The use of the plural spin injectors enabled to largely suppress the Joule heating of Py and the decrease in the spin diffusion length of Cu. They have shown large spin signals by the creation of the large pure spin current induced by applying large total bias currents of 8.0 mA with four-terminal Py spin injectors.[18]
The use of highly spin-polarized F materials as spin injectors is another method for large pure spin currents

Summary

Introduction

Generation and detection of spin currents in a nonmagnet (N) is an important technique for spintronic devices.[1,2] In particular, pure spin currents, the flow of spin angular moment without net charge current, can be generated by the nonlocal spin injection method in laterally arranged ferromagnet (F)/N/F spin-valve structures, which are so-called lateral spin valves (LSVs).[3,4,5,6,7,8,9] The use of LSVs for the pure spin currents enabled to observe new phenomena such as spin Hall effect,[10,11] spin-dependent Seebeck effect,[12,13] spin-dependent Peltier effect,[14,15] and so on. That the large spin signals with Co-based Heusler alloys at room temperature.[23,24,25] To further enhance the generation of pure spin currents in N without the degradation of the spin signals by high bias currents, the combination of the multi-terminal spin-injection technique and the highly spin-polarized Heusler-alloy spin injectors should be taken into account.

Results

Conclusion