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Center for Nonlinear Studies |
We briefly review the general area of spintronics, from the Nobel Prize-winning discovery of Giant Magnetoresistance to the subsequent prediction and observation of Spin-Transfer torque and its inverse of Spin-Pumping. We also discuss the parallel predictions by Dyakonov and Perel (1971), and Hirsch (1999), of the spin Hall Effect (SHE) and the inverse spin Hall effect (ISHE), and of their observation and use as a measurement tool. (A 2010 Nature article by Kagiwada et al provides a means to discuss all four of these phenomena.) For a proper understanding of these out-of-equilibrium phenomena, to the usual magnetization M one must also consider the out-of-equilibrium magnetization m (also known as spin accumulation). Using the framework provided by Onsager’s theory of irreversible thermodynamics, we discuss charge and spin transport in bulk and across interfaces, and the equations of motion and boundary conditions satisfied by M and by m. We also discuss which properties of M and m survive the transition from conductors to insulators, and survive from ferromagnets to paramagnets.
Host: Fuxiang Li