Quantitative and systematic analysis of bias dependence of spin accumulation voltage in a non-degenerate Si spin valve

TL;DR

This paper investigates how bias current affects spin accumulation voltages in a non-degenerate silicon spin valve, clarifying the origin of deviations observed experimentally through combined experiments and model calculations.

Contribution

It provides a systematic analysis linking bias dependence of resistance-area product to deviations in spin voltage measurements, highlighting the role of conductance mismatch.

Findings

Bias dependence of resistance-area product causes deviations in spin voltage.

Model calculations align with experimental results.

Conductance mismatch reappears under bias, affecting spin signals.

Abstract

Spin accumulation voltages in a non-degenerate Si spin valve are discussed quantitatively as a function of electric bias current using systematic experiments and model calculations. As an open question in semiconductor spintronics, the origin of the deviation of spin accumulation voltages measured experimentally in a non-degenerate Si spin valve is clarified from that obtained by model calculation using the spin drift diffusion equation including the effect of the spin-dependent interfacial resistance of tunneling barriers. Unlike the case of metallic spin valves, the bias dependence of the resistance-area product for a ferromagnet/MgO/Si interface, resulting in the reappearance of the conductance mismatch, plays a central role to induce the deviation.