Multiple transfer of angular momentum quanta from a spin-polarized hole to magnetic ions in ZnMnSe/ZnBeSe quantum wells

TL;DR

This study investigates ultrafast magnetization dynamics in quantum wells, revealing a dominant mechanism where spin-polarized holes transfer multiple angular momentum quanta to magnetic ions, significantly affecting magnetization within 100 ps.

Contribution

It introduces a model explaining multiple angular momentum transfer from spin-polarized holes to Mn ions, highlighting a new dominant process in magnetization dynamics.

Findings

Up to 30% reduction in magnetization within 100 ps after excitation

Complete spin polarization of carriers suppresses flip-flop processes

Multiple angular momentum transfer from holes to Mn ions identified as key mechanism

Abstract

The magnetization kinetics in (Zn,Mn)Se/(Zn,Be)Se quantum wells has been studied on a ps-time scale after pulsed laser excitation. The magnetization induced by an external magnetic field is reduced by up to 30% during ~100 ps due to spin and energy transfer from photocarriers to Mn spin system. The giant Zeeman splitting leads to a complete spin polarization of the carriers, resulting in a strong suppression of flip-flop processes between carriers and magnetic ions. Therefore a multiple angular momentum transfer from each spin-polarized hole to the Mn ions becomes the dominant mechanism in the magnetization dynamics. A model based on spin-momentum coupling in the valence band is suggested for explaining this transfer.