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Electron paramagnetic resonance and electron‐nuclear double resonance of nonequivalent Yb 3+ centers in stoichiometric lithium niobate
Author(s) -
Malovichko Galina,
Bratus Victor,
Grachev Valentin,
Kokanyan Edward
Publication year - 2009
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200844164
Subject(s) - ytterbium , electron paramagnetic resonance , hyperfine structure , lithium niobate , lithium (medication) , electron , electron nuclear double resonance , resonance (particle physics) , atomic physics , ion , nuclear magnetic resonance , chemistry , materials science , condensed matter physics , doping , physics , medicine , optoelectronics , organic chemistry , endocrinology , quantum mechanics
Abstract Lithium niobate crystals doped with ytterbium were studied using Electron Paramagnetic Resonance (EPR) and Electron Nuclear Double Resonance (ENDOR). The tremendous narrowing of EPR lines in nearly stoichiometric samples, when compared to those in congruent samples, allowed us to distinguish nine non‐equivalent centers, as well as line splitting caused by the hyperfine interaction of ytterbium electrons with the nuclear spins of two magnetic isotopes, 171 Yb and 173 Yb. Eight of the nine centers are described for the first time. It was found that three of the centers have axial C 3 symmetry, and all others have the lowest C 1 symmetry due to the presence of intrinsic defects and/or charge compensation defects in the near neighborhood of Yb 3+ . Characteristics of the g ‐tensor for all of the centers and hyperfine tensors for axial centers were determined. The ENDOR observations of Nb nuclei in the nearest neighborhood of Yb 1 3+ gave direct evidence that the dominated axial Yb 1 center has no charge compensator in its nearest surroundings (distant charge compensation mechanism). Both the EPR and ENDOR data for the main axial ytterbium center are explained by a supposition that Yb 3+ ions substitute for Li + . Possible models for low‐symmetry centers are discussed. The obtained numerous spectroscopic parameters can be used as cornerstones for model calculations of Yb 3+ centers in lithium niobate. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)