Abstract:

We find that in order to completely describe the spin transport, apart from the spin current (or the linear spin current), one has to introduce the angular spin current. The two spin currents respectively describe the translational and rotational motion of a spin. Both spin current densities appear naturally in the spin continuity equation. Moreover we predict that the angular spin current, just like the linear spin current, can also induce an electric field. In the second topic, the spin-orbit coupling systems with a zero magnetic field is studied under the equilibrium situation, i.e., without a voltage bias. A persistent spin current is predicted to exist under most circumstances, although the persistent charge current and the spin accumulation are identically zero. In addition, various semiconductor spin devices using spin-orbit interaction are proposed.
 
 
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