Diffusion of two dimensional magnetoexcitons

The two dimensional diffusion of single excitons in GaAs/AlGaAs quantum wel ls has been measured, at 4.2 K and in magnetic fields B up to 12 T, using s patially-resolved photoluminescence spectroscopy. At zero field an exceptio nally high diffusion constant D (600 cm(2)/s) has been found, which reduces quadratically with the application of a small B, due to the field induced increase of the excitonic mass. For higher magnetic fields the diffusion co nstant decreases as D similar to B-2, in agreement with theoretical predict ions which include quantum corrections in the exciton motion. (C) 2001 Else vier Science B.V. All rights reserved.