Non-thermal photocoercivity effect in a ferromagnetic semiconductor

TL;DR

This paper demonstrates a non-thermal, light-induced change in coercivity in a ferromagnetic semiconductor, enabling reversible magnetic patterning through localized light exposure.

Contribution

It reveals a non-thermal photocoercivity effect in (Ga,Mn)As and proposes a mechanism involving light-induced lowering of domain wall pinning energy.

Findings

PCE correlates with sample resistivity.

Thermal heating is ruled out as the cause of PCE.

PCE enables reversible, local magnetic writing and erasing.

Abstract

We report a photoinduced change of the coercive field, i.e., a photocoercivity effect (PCE), under very low intensity illumination of a low-doped (Ga,Mn)As ferromagnetic semiconductor. We find a strong correlation between the PCE and the sample resistivity. Spatially resolved dynamics of the magnetization reversal rule out any role of thermal heating in the origin of this PCE, and we propose a mechanism based on the light-induced lowering of the domain wall pinning energy. The PCE is local and reversible, allowing writing and erasing of magnetic images using light.