Experimental observation of the optical spin-orbit torque
Abstract
Electrical and optical control of magnetization are of central importance in the research and applications of spintronics. Non-relativistic angular momentum transfer or relativistic spin-orbit coupling provide efficient means by which electrical current driven through a ferromagnet can exert a torque on the magnetization. Ferromagnetic semiconductors like (Ga,Mn)As are suitable model systems with which to search for optical counterparts of these phenomena, where photocarriers excited by a laser pulse exert torque upon magnetization. Here, we report the observation of an optical spin-orbit torque (OSOT) in (Ga,Mn)As. The phenomenon originates from spin-orbit coupling of non-equilibrium photocarriers excitated by helicity-independent pump laser pulses, which do not impart angular momentum. In our measurements of the time-dependent magnetization trajectories, the signatures of OSOT are clearly distinct from the competing thermal excitation mechanism, and OSOT can even dominate in (Ga,Mn)As materials with appropriately controlled micromagnetic parameters.
- Publication:
-
Nature Photonics
- Pub Date:
- June 2013
- DOI:
- 10.1038/nphoton.2013.76
- arXiv:
- arXiv:1207.0307
- Bibcode:
- 2013NaPho...7..492T
- Keywords:
-
- Condensed Matter - Materials Science
- E-Print:
- 4 figure, supplementary information. arXiv admin note: text overlap with arXiv:1101.1049