PICOSECOND DYNAMICS OF MAGNETIC POLARONS GOVERNED BY ENERGY-TRANSFER TO THE ZEEMAN RESERVOIR

We suggest a mechanism of magnetic polaron formation in semimagnetic q uantum wells in external magnetic fields, which is characterized by a transfer of energy from the carrier-magnetic-ions exchange reservoir t o the Zeeman reservoir. This mechanism is related to the anisotropic e xchange interaction due to the spin structure of the heavy-hole state. The polaron formation is determined by a precession of a total spin o f magnetic ions inside the exciton volume in the sum of external and e xchange field and happens inside the short time of about 10 ps. Experi mentally, this mechanism manifests itself in photoluminescence spectra as an increase of the magnetic polaron shift at magnetic fields appli ed parallel to the quantum-well plane.