OPTICAL-DETECTION OF SPIN RELAXATION OF 2D-ELECTRONS DURING PHOTOEXCITATION

Direct optical detection of the relaxation of the spin orientation of 2D electrons in a quantizing magnetic field has been achieved under co nditions such that the corrections for the exchange interaction of the spins of an electron spin and a photoexcited hole are reduced to zero . This is the first such detection. The time scale of the relaxation t o a spin equilibrium has been found through time-resolved measurements to be on the order of 5 ns in a field of 2.6 T. The spin relaxation s lows down as the index of the Landau level decreases and as the magnet ic field simultaneously increases. The experimental results point to s pin-flip mechanisms involving a spin-orbit interaction.