A variable temperature EPR study of Cu2+ doped single crystals of pyrovanadates β-Mg2V2O7, α-Zn2V2O7: estimations of non-coincident g2- and A2-tensors
https://doi.org/10.26907/mrsej-19502
Abstract
Full angular variations of Cu2+ EPR spectra in β-Mg2V2O7 (MgVO) and α-Zn2V2O7 (ZnVO) were recorded for orientations of external magnetic field in three mutually perpendicular planes at 120 K and 295 K, as well as in temperature range from 110 to 295 K at some chosen orientations of magnetic field. The principal values of the g2- and A2-tensors, as well as the orientations of their principal axes were determined from angular variations of EPR line positions in three mutually perpendicular planes, using a rigorous least square fitting procedure, especially adapted to the case of non-coincident principal axes of the A2-tensors for the monoclinic and triclinic point-group symmetries in MgVO and ZnVO crystals, respectively. This procedure uses the eigenvalues and eigenvectors of the spin-Hamiltonian matrix, which allows to determine the orientations of the principal axes of the g2 (Zeeman) and A2 (hyperfine-interaction)-tensors. It is found, that the principal values of g2- and A2-tensors of the Cu2+ ions are similar in the two crystals; however, the orientations of the principal axes of these tensors are significantly different from each other. This is because the Cu2+ ion in MgVO is 6-fold coordinated, whereas it is 5-fold coordinated in trigonal bipyramidal coordination in ZnVO. The principal values of the g2-tensor, so obtained, are exploited to determine the electronic ground state of the Cu2+ ion in these two crystals.
Supporting agencies: SIA is grateful for a partial financial support in the frame of research project, allocated to Kazan Federal University, Russia, from the Russian Ministry of Education and Science (3.2166.2017/4.6).
About the Authors
S. K. Misra
Physics Department, Concordia University
Canada
Canada
Montreal, QC, H3G 1M8
S. I. Andronenko
Institute of Physics, Kazan Federal University
Russian Federation
Russian Federation
Kremlevskaya 18, Kazan 420008
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Review
For citations:
Misra S.K., Andronenko S.I. A variable temperature EPR study of Cu2+ doped single crystals of pyrovanadates β-Mg2V2O7, α-Zn2V2O7: estimations of non-coincident g2- and A2-tensors. Magnetic Resonance in Solids. 2019;21(5):19502 (11 pp.). https://doi.org/10.26907/mrsej-19502
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