EPR of Nd3+ in congruent and nearly stoichiometric lithium niobate

Abstract

Lithium niobate crystals doped with neodymium were studied with the help of electron paramagnetic resonance, EPR in the temperature range of 4.2-20 K. Tremendous narTowing of the EPR lines in nearly stoichiometric samples in comparison with congruent ones allowed us to distinguish four non-equivalent centers, as well as line splitting caused by hyperfine interaction of neodymium electrons with nuclear spins of both magnetic isotopes Nd-143 and Nd-145. It is shown that one of the centers has axial C-t symmetry, whereas all others have lowest C-t symmetry due to presence of intrinsic defects or/and charge compensation defects in the near neighborhood of Nd3+.