Angular and temperature dependencies of EPR linewidth and Gorter relaxation rates in concentrated paramagnets: Application to La0.9Sr0.1MnO3 and La0.875Sr0.125MnO3
Abstract
The angular and temperature dependencies of the electron paramagnetic resonance (EPR) linewidth in the weak constant field and of the relaxation rates measurable by the Gorter type experiments in zero constant magnetic field (Gorter RRs) are analytically investigated in magnetically concentrated paramagnets with the dominating exchange interaction. The consideration is restricted to the experiments, where the EPR linewidth is both anisotropic and linear over the temperature. It is suggested that under such conditions the EPR broadening is caused by the spin-lattice relaxation of the anisotropic interaction via the one-phonon mechanism. The analytical results are brought to the form suitable for the extraction of the Dzyaloshinsky-Moriya and the crystal field interaction constants from the experiment. It is shown that the EPR linewidth at the constant field direction along any crystal axis is equal to the half sum of the zero-field RRs for the two other crystal axes. The obtained results are successfully used for the interpretation of the EPR experimental results in the La0.9Sr0.1MnO3 and La0.875Sr0.125MnO3 single crystals in the Jahn-Teller strongly distorted phase in the definite temperature interval. The angular dependencies of the Gorter RRs and the EPR linewidth are presented graphically at the constant field continuous rotations in the three crystallographic planes in La0.9Sr0.1MnO3.
Keywords
Supporting agencies: The financial support of Shota Rustaveli National Science Foundation, Georgia (grant № FR/299/6-110/14) is gratefully acknowledged.
About the Authors
E. Kh. Khalvashi
Batumi Shota Rustaveli State University
Georgia
Georgia
Ninoshvili str. 35, Batumi 6010
N. P. Fokina
Department of Science, Georgian Technical University
Georgia
Georgia
Kostava str. 77, Tbilisi 0175
M. O. Elizbarashvili
Vladimir Chavchanidze Institute of Cybernetics, Georgian Technical University
Georgia
Georgia
Sandro Euli str. 5, Tbilisi 0186
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Review
For citations:
Khalvashi E.Kh., Fokina N.P., Elizbarashvili M.O. Angular and temperature dependencies of EPR linewidth and Gorter relaxation rates in concentrated paramagnets: Application to La0.9Sr0.1MnO3 and La0.875Sr0.125MnO3. Magnetic Resonance in Solids. 2017;19(1):17101 (17 pp.).
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