EPR study of low symmetry Er centers in congruent lithium niobate

Electron paramagnetic resonance study of congruent LiNbO3 single crystal weakly doped (0.1 wt%) with erbium is reported. The EPR lines originating both from the 167Er isotope with a hyperfine structure, as well as from the evenEr isotopes causing fine structure, are identified. Angular dependence of the EPR lines reveals the presence of several non-equivalent centers. Deconvolution of the EPR line into several Lorentzian components in a plane perpendicular to the z-axis (optical c-axis) allowed us to show the Er3+ center with the lowest (C1) point group symmetry and estimate the values of g-tensor. The obtained results confirmed the model of non- equivalent centers of the rare-earth ions in lithium niobate having the lowest C1 symmetry due to the presence of intrinsic defects in the near-neighborhood of RE3+. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)