Spin injection in the non-linear regime: band bending effects

TL;DR

This paper investigates how spin injection efficiency decreases in semiconductor heterostructures under high bias, attributing the effects to band bending and charge accumulation at the interface, with a model extension to explain the phenomena.

Contribution

The study extends the charge-imbalance model to include band bending and charge accumulation, providing new insights into non-linear spin injection effects in semiconductor heterostructures.

Findings

Spin injection efficiency decreases at biases of a few mV.

Band bending and charge accumulation influence spin injection.

Repopulation of minority spin levels explains the observed effects.

Abstract

Semiconductor spintronics will need to control spin injection phenomena in the non-linear regime. In order to study these effects we have performed spin injection measurements from a dilute magnetic semiconductor [(Zn,Be,Mn)Se] into nonmagnetic (Zn,Be)Se at elevated bias. When the applied voltage is increased to a few mV we find a strong decrease of the spin injection efficiency. The observed behavior is modelled by extending the charge-imbalance model for spin injection to include band bending and charge accumulation at the interface of the two compounds. We find that the observed effects can be attributed to repopulation of the minority spin level in the magnetic semiconductor.