Abstract:

In the last decade, the large field of semiconductor spin physics has proven fruitful for new interesting physics.
In the first part of my talk I present a new approach to the old problem of Bose-Einstein-Condensation of semiconductor excitons. The new approach utilizes partly spin polarized excitons for revealing an - otherwise invisible - fingerprint of a degenerate gas of excitons and biexcitons on its route to condensation. We theoretically predict, that the photoluminescence polarization at the biexciton line turns from unpolarized before condensation to highly polarized in the case of a condensate. Preliminary measurements show indeed an onset of circular polarization at the biexciton emission line in ZnSe and GaAs quantum wells when conditions for condensation are approached at high carrier densities and low temperatures.
In the second part of my talk I give a short heuristic derivation of anisotropic spin relaxation rates and present recent measurements of the spin relaxation tensor in bulk n-GaN.
 
 
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