Comparison between a quantum kinetic theory of spin transfer dynamics in Mn doped bulk semiconductors and its Markov limit for non-zero Mn magnetization

TL;DR

This paper compares a detailed quantum kinetic model of spin transfer in Mn-doped semiconductors with its Markov approximation, revealing significant differences at finite Mn magnetization due to quantum effects.

Contribution

It introduces a quantum kinetic framework for spin transfer dynamics and analyzes the limitations of the Markov limit in systems with non-zero Mn magnetization.

Findings

Markov approximation aligns with quantum kinetics at zero Mn magnetization.

Significant deviations occur at finite Mn magnetization due to higher-order quantum effects.

Quantum corrections influence spin transfer dynamics beyond classical rate equations.

Abstract

We investigate the transfer between carrier and Mn spins due to the s-d-exchange interaction in a Mn doped bulk semiconductor within a microscopic quantum kinetic theory. We demonstrate that the spin transfer dynamics is qualitatively different for components of the carrier spin parallel and perpendicular to the Mn magnetization. From our quantum kinetic equations we have worked out the corresponding Markov limit which is equivalent to rate equations based on Fermi's golden rule. The resulting equations resemble the widely used Landau-Lifshitz-Gilbert-equations, but also describe genuine spin transfer due to quantum corrections. Although it is known that the Markovian rate description works well for bulk systems when the initial Mn magnetization is zero, we find large qualitative deviations from the full quantum kinetic theory for finite initial Mn magnetizations. These deviations mainly reflect corrections of higher than leading order in the interaction which are not accounted for in golden rule-type rates.