Optical Properties of GaFeO_3

摘要

The complex dielectric function epsilon and critical-point (CP) structures of orthorhombic GaFeO3 are reported at temperatures from 39 to 350 K and photon energies from 0.74 to 6.42 eV. Data were obtained by rotating-compensator spectroscopic ellipsometry on the (010) direction of single-crystalline GaFeO3. A multilayer version of the B-splines method was used to extract the optical properties of GaFeO3, and CP energies were accurately determined by analyzing numerically calculated second-energy-derivatives of the data. At low temperature the CP structures are clearly enhanced and their energies are blue-shifted. Temperature dependencies were obtained by fitting the data to a phenomenological expression that contains a Bose-Einstein statistical factor and a temperature coefficient.