Peculiarity of the EPR spectra of impurity Gd ions in lead telluride single crystals

Abstract

EPR spectra of the impurity Gd ions in PbTe crystal matrix were investigated at both room and liquid nitrogen temperatures. Origin of the EPR fine structure spectra consisting of seven lines, which is typical for non-interacting paramagnetic ions in the ground 8S 7/2 state, was studied. Two peculiar features were observed. First, the positions of the fine structure lateral lines were always asymmetric with respect to the central line. Second, the line intensities ratio did deviate from the theoretical prediction 16:12:15:7 for a paramagnetic S= 7 2 ion in cubic crystal field. Preliminary spin Hamiltonian analysis has been carried out based on the assumption of cubic site symmetry. Experimental results indicate that the simplified model cannot fully explain the observed feature of EPR spectra of Gd ions in the Gd 3+ ( 8S 7/2) charge state. The components of a predominantly cubic complex formed by substituting Gd dopant ion and a tellurium vacancy V Te are considered. Further studies taking into account lower symmetry distortions of the Gd 3+−V Te complex are in progress.