Spin conservation of photocreated carriers in quantum wells in high magnetic fields: A new spectroscopic tool

The spin relaxation of photocreated carriers in GaAs/GaAlAs quantum wells in high magnetic fields is investigated by luminescence experiments under selective optical excitation. The complete quantization of the two-dimensional energy structure in high magnetic fields implies a simultaneous exchange of energy and momentum for spin relaxation and makes spin-conserving relaxation processes, both in thermalization and recombination, much faster than spin-flip processes. This results in a new spectroscopic tool to identify magnetoexcitonic states with the same electronic spin orientation.