Condensed Matter Seminars

Spintronics is an interdisciplinary field in which the central idea is the manipulation of spin degrees of freedom in solid state systems. The motivation to examine spintronics ranges from fundamental studies, where the changes of the spin degrees of freedom can be a sensitive probe for basic physical phenomena, to applications that are neither feasible nor effective with conventional electronics. This talk will focus on two examples: (1) spin-polarized transport in hybrid structures containing superconductors and (2) a proposal for magnetic p-n junctions. Our prediction that a superconducting response can be used to probe a novel class of ferromagnetic semiconductors has recently led to the first direct measurement of the spin polarization in these materials. In the second example, we develop a theory of inhomogeneously doped semiconductors. We predict the spin-voltaic effect, a spin-analogue of the photo-voltaic effect. We show that the direction of the charge current (which can even flow at no applied bias) can be switched by the reversal of an equilibrium magnetization or of a polarization of the injected spin. The same spin-voltaic effect can be used to develop a novel class of tunable magnetic transistors.