Special features of the Faraday effect in rare earth orthoaluminate TbAlO3

Abstract

The luminescence excitation spectra (LES) and luminescence (fluorescence) spectra of terbium orthoaluminate TbAlO3 have been studied within the wavelength range 150–350 nm and 450–700 nm, respectively, and within the temperature range 25–300 K. Based on the results of studying the LES within the wavelength range 220–260 nm, it has been concluded that in the same range there is an intense optical absorption band due to the allowed (in the electric dipole approximation) transition 4f(8)(F76)→4f(7)5d(eg). While measuring the Faraday effect (FE) in TbAlO3 the spectral dependence of the rotation angle θ of the major axis of the polarization ellipse has been investigated for temperature 300 K over the visible and near ultraviolet (UV) spectral range 250–400 nm. From the analysis of the data of magneto-optical studies, the frequency dependence of the Verde constant of TbAlO3 in the UV spectral range has been restored. The behavior of the FE frequency dependence for the absorption band of the 220–260 wavelength indicates that there is a “paramagnetic” contribution to the Verdet constant caused by allowed (in the electric dipole approximation) transitions occurring from the Stark sublevels of the ground 7F6 multiplet to the states of the mixed excited configuration 4f(7)5d of the rare-earth Tb3+ ion in orthoaluminate.