Topological Insulator Surface States for Spintronics

Spintronics is the study of the mutual influence between charge transport in conductors and charge neutral spin degrees of freedom, especially the collective spin degrees of freedom of magnetically ordered systems. The effects of spintronics all require coupling between spin and orbital degrees of freedom. Systems containing thin-films of three dimensional topological insulators (TIs) are in many cases ideal hosts for spintronics studies becasue of the strong spin-orbit coupling present in the protected TI surface states, which can also serve as an isolated two-dimensional charge transport channel. I will discuss theories of the closely related anomalous Hall, spin Hall, spin-orbit torque, magneto-resistance, and spin-pumping effects in isolated TI thin films, and in TI thin films proximity coupled to conducting and insulating ferromagnets and antiferromagnets. My talk will focus on discussing possible applications of topological insulators in thin-film devices for electrically controlled magnetism, and emphasize the separate roles played by top and bottom TI surfaces.