HIGH-PRESSURE STUDY OF PHOTOLUMINESCENCE SPECTRA IN MAGNETIC SEMICONDUCTOR EUSE

The pressure dependence of the photoluminescence spectra in EuSe crystals has been studied up to 2.0 GPa at 77 K and 1.8 K using a diamond anvil cell. At 77 K, the pressure derivative of the peak position of the photoluminescence band is found to be -96 meV/GPa, which coincides with the pressure derivative of the absorption edge. The result supports 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 about 50 meV with the increase of the pressure beyond 0.4 approximately 0.5 GPa. Observed anomalies are interpreted in terms of the pressure-induced phase transition from the antiferromagnetic to the ferromagnetic phase, where the magnetic polaron effect plays a significant role.