Optical spin-transfer-torque-driven domain-wall motion in a ferromagnetic semiconductor

Phys Rev Lett. 2015 Feb 13;114(6):067202. doi: 10.1103/PhysRevLett.114.067202. Epub 2015 Feb 11.

Abstract

We demonstrate optical manipulation of the position of a domain wall in a dilute magnetic semiconductor, GaMnAsP. Two main contributions are identified. First, photocarrier spin exerts a spin-transfer torque on the magnetization via the exchange interaction. The direction of the domain-wall motion can be controlled using the helicity of the laser. Second, the domain wall is attracted to the hot spot generated by the focused laser. Unlike magnetic-field-driven domain-wall depinning, these mechanisms directly drive domain-wall motion, providing an optical tweezerlike ability to position and locally probe domain walls.