Abstract:

Spin-orbit coupling makes the electron spin degree of freedom respond to its orbital environ- ment. Thus it gives us a "control knob" with which we can steer the purely quantum-mechanical spin degree of freedom. Recently, the electron spin and spin-orbit coupling have attracted much attention due to the possibility to complement conventional charge-based electronics by novel approaches that use also the electron's spin (spintronics).
In my talk I will provide a general introduction into the world of spinning electrons [1], followed by the discussion of a few examples for the rich and fascinating physics that emerges from the interplay between the spin and orbital dynamics of electrons in solids. Similar to an external magnetic field, spin-orbit coupling can give rise to spin precession. In the presence of a driving electric field the steady-state nonequlibrium density matrix contains a precessing component describing the formation of spin currents. A second nonequilibrium component which does not precess turns out to be responsible for the electric generation of spin densities [2].
A decomposition of the spin-orbit coupled dynamics in multiple bands into a smooth part and an oscillatory part is well-known from relativistic quantum mechanics, where an oscillatory component in the orbital dynamics has been called zitterbewegung. We will show that the generation of spin currents and spin densities in semiconductors is closely related with the phenomenon of zitterbewegung of Dirac electrons [3].
[1] R. Winkler, Spin-Orbit Coupling Effects in Two-Dimensional Electron and Hole Systems (Springer, Berlin, 2003).
[2] D. Culcer and R. Winkler, Phys. Rev. Lett. 99, 226601 (2007).
[3] R. Winkler, U. Z \u0308licke, and J. Bolte, Phys. Rev. B 75, 205314 (2007). u
 
 
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