MODIFICATION OF FANO RESONANCES BY RESONANT POLARON COUPLING IN BULK GAAS

Strong modifications of the magneto-excitonic Fano lineshapes have bee n observed in the photoluminescence-excitation spectra of bulk GaAs wh en the energies of the transitions are tuned by an external magnetic f ield. We identify the origin of these changes as resonant polaronic co upling between the electrons or holes, forming the excitons, with long itudinal-optical phonons, in conduction and valence bands respectively . The resonant polaron effect alters the magneto-excitonic discrete st ates, destroying the quantum interferences responsible for the Fano as ymmetry.