Title: Theory of spin transport in spin-orbit coupling systems

Abstract:We theoretically investigated the generation of spin current and spin polarization in spin-orbit coupling (SOC) systems. First, we studied the spin transport in a time-dependent Rashba system, where the Rashba coupling is modulated by an AC gate voltage. At high Rashba frequency, we showed that the electron spin polarization can be rectified. As a consequence, the Zitterbewegung of electron wave packet in such system can be kept persistent, which is significant for the experimental observation. In addition, by combining time-dependent Rashba and Dresselhaus SOCs, we proposed a method to generate spin current that is sustainable in disordered systems. Moreover, in ballistic limit, such systems can be utilized as a source for spin pumping. In the next part of the thesis, we unified the description of spin Hall effects in a wide class of SOC systems by using spin force picture, which reproduced the spin Hall conductivity obtained previously via Kubo's linear response approach.