Femtosecond spin-polarization spectroscopy in diluted-magnetic-semiconductor quantum wells

Charge-carrier spin scattering in diluted-magnetic-semiconductor multiple quantum wells is directly observed through the circular polarization of luminescence in a femtosecond time-resolved measurement. This represents a new short-time regime for direct spin-relaxation studies. Separate observations of electron and hole relaxation are accomplished by varying the applied magnetic field. Surprisingly, the spin-flip scattering rates in these systems appear to be independent of the extremely strong spin-spin–exchange interaction between the charge carriers and the magnetic ions.