All-optical generation and control of spin currents

The control of spin for technological purposes, known as spintronics, is usually discussed in terms of how one can use specially prepared materials (e.g., ferromagnetic semiconductors) or nanogeometries to manipulate spin, via electrical potentials. In recent years we, together with students and postdoctoral fellows, have explored how optics may contribute to spin manipulation and control. Since a photon's energy is large compared to that required to flip a spin, optical techniques may not satisfy requirements of low energy consumption, but advantages related to speed, manipulation without electrical contacts, and the ability to control the magnitude and vector direction of spin currents may enable optical techniques to find application in certain niche areas.