Optical and magneto-optical studies of a multiferroic GaFeO3 with a high curie temperature

Abstract

Single crystals of a noncentrosymmetric orthorhombic pyroelectric ferrimagnet Ga2 -xFexO3 with a Curie temperature within 260-345 K have been grown by the flux method. It has been found that the electrical properties of the single crystals varied over a broad range from 105 to 1013 Ω cm depending on the presence of transition-metal oxide impurities. The dispersion relations for all three principal dielectric functions of orthorhombic GaFeO3 have been determined in the range 0.7-5.4 eV by spectroscopic ellipsometry. The spectra of the dielectric functions of the orthorhombic Ga2 -xFexO3 crystals are compared with the spectra of the trigonal crystals. The Faraday effect and second-harmonic generation are studied, and the law of the transition to the paramagnetic state has been determined. The crystallographic and magnetic contributions to the second-harmonic generation are analyzed. © 2005 Pleiades Publishing, Inc.