DYNAMICS OF THE MAGNETIC POLARON FORMATION IN ZNSE ZNMNSE QUANTUM-WELL STRUCTURES/

We have performed time-resolved photoluminescence spectroscopy of ZnSe /ZnMnSe quantum wells with semimagnetic barriers in a magnetic field. The data demonstrate a change of the dominant energy relaxation mechan ism from disorder localization of light-hole excitons at zero field to heavy-hole exciton magnetic polaron formation at intermediate fields and, again, disorder localization of heavy-hole excitons at large magn etic fields, The transient polaronic shift is directly resolved and is described by a formation time of 110 ps at B = 2 T which decreases wi th growing magnetic field down to 70 ps at B = 5 T. The polaron format ion is preceded by a fast initial localization of magnetic origin.