Abstract:

The spin Hall eect, i.e., the generation of a transverse spin current from a charge current and viceversa, has attracted much attention in the past decade: it has now become one of the standard tools for the generation and detection of spin currents in magneto-electronic devices. In this talk I address the ques- tion of how the eect manifests itself in the dynamics of collective states, e.g. an electron-hole density wave induced by optical excitation on the surface of n-doped GaAs. It has recently been predictedy that an electric eld parallel to the wavefronts of an electron-hole grating in a GaAs quantum well generates, via the electronic spin Hall eect, a spin grating of the same wave vector and with an amplitude that can exceed 1% of the amplitude of the initial density grating { an observable eect. I refer to this phenomenon as \collective spin Hall eect". A detailed study of the coupled-spin charge dynamics for quantum wells grown in dierent directions reveals rich features in the time evolution of the induced spin density, including the possibility of generating a helical spin grating from a density grating.
 
 
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