Electronic transport driven spin-dynamics

TL;DR

This paper introduces a model to understand spin dynamics in a ferromagnet/semiconductor/ferromagnet structure, explaining transient transport signatures through current-driven Mn spin polarization and its temperature dependence.

Contribution

The paper presents a quantitative model linking spin-polarized transport and dynamical Mn spin polarization in a spin-valve structure, explaining recent experimental observations.

Findings

Transient transport signatures are explained by current-driven Mn spin polarization.

The model reproduces the temperature scaling of transient features.

Dynamical equations capture the coupling between conduction electrons and Mn impurities.

Abstract

We propose a model to explore the dynamics of spin-systems coupled by exchange interaction to the conduction band electrons of a semiconductor material that forms the channel in a ferromagnet/semiconductor/ferromagnet spin-valve structure. We show that recent observation of the novel transient transport signature in a MnAs/GaAs/MnAs spin-valve structure with paramagnetic Mn impurities [D. Saha et al., Phys. Rev. Lett., 100, 196603 (2008)] can be quantitatively understood in terms of current driven dynamical polarization of Mn spins. Using our model of spin polarized transport through Schottky barriers at the two ferromagnet/semiconductor junctions in a spin-valve structure and a dynamical equation describing the paramagnetic impurities coupled to conduction band electrons we explain the scaling behaviour of observed transient features such as the magnitude and time-scale with temperature.