RAMAN-STUDY OF PRESSURE-INDUCED MAGNETIC PHASE-TRANSITION IN EUSE

Raman spectra of EuSe have been measured under hydrostatic pressure up to 2.1 GPa at 2 K by using a diamond anvil. With increasing pressure, distinct spectral changes occur twice, which can be interpreted in te rms of successive magnetic phase transition: ferri --> antiferro (AF-I ) --> ferro. The Raman peaks are attributed to phonons at special poin ts in the Brillouin zone taking account of the folding effect on the p honon dispersion. This makes it possible to draw overall features of t he dispersion curve of LO phonon along the [111] direction under high pressure.