Efficient nonlinear room-temperature spin injection from ferromagnets into semiconductors through a modified Schottky barrier

TL;DR

This paper develops a microscopic theory for efficient room-temperature spin injection from ferromagnets into semiconductors via a modified Schottky barrier, enabling near 100% spin polarization at low currents.

Contribution

It introduces a new theoretical model for spin injection through a modified Schottky barrier, highlighting conditions for maximal spin polarization in resistive semiconductors.

Findings

Spin polarization can approach 100% at room temperature.

Optimal spin injection occurs in lightly doped, resistive semiconductors.

Nonlinear I-V characteristics and current saturation are predicted.

Abstract

We suggest a consistent microscopic theory of spin injection from a ferromagnet (FM) into a semiconductor (S). It describes tunneling and emission of electrons through modified FM-S Schottky barrier with an ultrathin heavily doped interfacial S layer . We calculate nonlinear spin-selective properties of such a reverse-biased FM-S junction, its nonlinear I-V characteristic, current saturation, and spin accumulation in S. We show that the spin polarization of current, spin density, and penetration length increase with the total current until saturation. We find conditions for most efficient spin injection, which are opposite to the results of previous works, since the present theory suggests using a lightly doped resistive semiconductor. It is shown that the maximal spin polarizations of current and electrons (spin accumulation) can approach 100% at room temperatures and low current density in a nondegenerate high-resistance semiconductor.