Ferromagnetic imprinting of spin polarization in a semiconductor

TL;DR

This paper develops a theoretical model explaining how ferromagnetic interfaces can imprint and manipulate electron spin coherence and polarization in semiconductors, with potential for spintronic device control.

Contribution

It introduces a new theory describing spin imprinting via electron reflection at ferromagnet-semiconductor interfaces, including effects of barrier height and doping.

Findings

Reflection induces spontaneous electron spin coherence.

Spin polarization depends on Schottky barrier and doping.

Potential control mechanisms for spintronic devices.

Abstract

We present a theory of the imprinting of the electron spin coherence and population in an n-doped semiconductor which forms a junction with a ferromagnet. The reflection of non-equilibrium semiconductor electrons at the interface provides a mechanism to manipulate the spin polarization vector. In the case of unpolarized excitation, this ballistic effect produces spontaneous electron spin coherence and nuclear polarization in the semiconductor, as recently observed by time-resolved Faraday rotation experiments. We investigate the dependence of the spin reflection on the Schottky barrier height and the doping concentration in the semiconductor and suggest control mechanisms for possible device applications.