Observation of large spin accumulation voltages in non-degenerate Si spin devices due to spin drift effect: Experiments and theory

TL;DR

This study reports the largest spin-accumulation voltage in non-degenerate silicon spin devices at room temperature, explained by a modified spin drift-diffusion model highlighting the impact of spin drift effects on magnetoresistance.

Contribution

The paper introduces a modified spin drift-diffusion model that accurately explains large spin voltages and bias dependence in silicon-based lateral spin valves, advancing understanding of spin transport.

Findings

Measured spin-accumulation voltage exceeds 1.5 mV at 1 mA.

The modified model accounts for bias-current-polarity dependence.

Spin drift effect enhances magnetoresistance in two-terminal schemes.

Abstract

A large spin-accumulation voltage of more than 1.5 mV at 1 mA, i.e., a magnetoresistance of 1.5 {\Omega}, was measured by means of the local three-terminal magnetoresistance in nondegenerate Si-based lateral spin valves (LSVs) at room temperature. This is the largest spin-accumulation voltage measured in semiconductor-based LSVs. The modified spin drift-diffusion model, which successfully accounts for the spin drift effect, explains the large spin-accumulation voltage and significant bias-current-polarity dependence. The model also shows that the spin drift effect enhances the spin-dependent magnetoresistance in the electric two terminal scheme. This finding provides a useful guiding principle for spin metal-oxide semiconductor field-effect transistor (MOSFET) operations.