Wide-Band EPR Spectroscopy of SrY2O4:Ho3+ Crystal

EPR spectra of impurity Ho3+ ions in oriented SrY2O4 single-crystals are registered at the temperature 4.2 K in the frequency range from 70 to 180 GHz. The results of measurements evidence for the substitution of Ho3+ ions for the Y3+ ions at the structurally nonequivalent sites R1 and R2 with the local Cs point symmetry. The values of g-factors, hyperfine structure constants and the energy gaps between the ground and the first excited non-degenherate crystal-field sublevels of the ground I-5(8) multiplet are determined. The observed specific features of the ground states of Ho3+ ions (non-Kramers doublets with the zero-field splittings of 4.30 and 1.67 cm(-1)) open a possibility to identify transitions in optical spectra of SrY2O4:Ho and inelastic neutron scattering spectra of SrHo2O4 crystals.