Spin polarization amplification within nonmagnetic semiconductors at room temperature

TL;DR

This paper presents a theoretical method to amplify spin polarization in nonmagnetic semiconductors at room temperature using a T-shaped geometry, achieving near 100% polarization without magnetic materials.

Contribution

It introduces a novel electric amplification scheme for spin polarization in nonmagnetic semiconductors, eliminating the need for ferromagnets or low temperatures.

Findings

Spin polarization can be amplified in nonmagnetic semiconductors.

Output spin polarization can reach 100% with proper electric field tuning.

The scheme operates efficiently at room temperature without magnetic materials.

Abstract

We demonstrate theoretically that the spin polarization of current can be electrically amplified within nonmagnetic semiconductors by exploiting the fact the spin current, compared to the charge current, is weakly perturbed by electric driving forces. As a specific example, we consider a T-shaped current branching geometry made entirely of a nonmagnetic semiconductor, where the current is injected into one of the branches (input branch) and splits into the other two branches (output branches). We show that when the input current has a moderate spin polarization, the spin polarization in one of the output branches can be higher than the spin polarization in the input branch and may reach 100% when the relative magnitudes of current-driving electric fields in the two output branches are properly tuned. The proposed amplification scheme does not use ferromagnets or magnetic fields, and does not require low temperature operation, providing an efficient way to generate a highly spin polarized current in nonmagnetic semiconductors at room temperature.