Control of spin injection by direct current in lateral spin valves

TL;DR

This paper demonstrates that direct current injection in lateral spin valves can reverse spin accumulation without changing its magnitude, with Joule heating significantly impacting the spin signals, supported by a spin-dependent diffusion model.

Contribution

It shows that DC current can control spin injection direction in lateral spin valves, revealing symmetric injection mechanisms and the impact of Joule heating.

Findings

Spin accumulation is reversed by current direction change.

Injection mechanism is symmetric for both current directions.

High current densities cause significant Joule heating affecting spin signals.

Abstract

The spin injection and accumulation in metallic lateral spin valves with transparent interfaces is studied using d.c. injection current. Unlike a.c.-based techniques, this allows investigating the effects of the direction and magnitude of the injected current. We find that the spin accumulation is reversed by changing the direction of the injected current, whereas its magnitude does not change. The injection mechanism for both current directions is thus perfectly symmetric, leading to the same spin injection efficiency for both spin types. This result is accounted for by a spin-dependent diffusion model. Joule heating increases considerably the local temperature in the spin valves when high current densities are injected ($\sim$80--105 K for 1--2$\times10^{7}$A cm$^{-2}$), strongly affecting the spin accumulation.