HIGH-PRESSURE STUDY OF PHOTOLUMINESCENCE SPECTRA IN MAGNETIC SEMICONDUCTOR EUSE

The pressure dependence of the photoluminescence spectra in EuSe cryst als has been studied up to 2.0 GPa at 77 K and 1.8 K using a diamond a nvil cell. At 77 K, the pressure derivative of the peak position of th e photoluminescence band is found to be -96 meV/GPa, which coincides w ith the pressure derivative of the absorption edge. The result support s the interpretation that the emitting state of the photoluminescence is the 5 d (t2g) state. At 1. 8 K, we have observed sharp decrease of the photoluminescence intensity and redshift of the peak energy of abo ut 50 meV with the increase of the pressure beyond 0.4 approximately 0 .5 GPa. Observed anomalies are interpreted in terms of the pressure-in duced phase transition from the antiferromagnetic to the ferromagnetic phase, where the magnetic polaron effect plays a significant role.