부산대학교 도서관

The transmission spectra of HoFe(BO) multiferroic single crystals are studied by optical Fourier-transform spectroscopy at temperatures of 1.7-423 K in polarized light in the spectral range 500-10 000 cm with a resolution up to 0.1 cm. A new first-order structural phase transition close to the second-order transition is recorded at T = 360 K by the appearance of a new phonon mode at 976 cm. The reasons for considerable differences in T for different samples of holmium ferroborate are discussed. By temperature variations in the spectra of the f-f transitions in the Ho ion, we studied two magnetic phase transitions, namely, magnetic ordering into an easy-plane structure as a second-order phase transition at T = 39 K and spin reorientation from the ab plane to the c axis as a first-order phase transition at T = 4.7 ± 0.2 K. It is shown that erbium impurity in a concentration of 1 at % decreases the spin-reorientation transition temperature to T = 4.0 K. [ABSTRACT FROM AUTHOR]