Effect of diamagnetic dilution on spin dynamics in manganites (in Russian)
Abstract
In the magnetically diluted LaMnxGa1-xO3 single crystals, the EPR spectra of the Mn ions (at 0.02 <= x <= 1), as well as NMR and nuclear spin-lattice relaxation of 69Ga and 71Ga nuclei have been investigated. The analysis of the EPR spectra enabled one to follow the exchange narrowing effect to the point of appearance of a single Lorentzian line at x >= 0.2. The transition from the antiferromagnetic to ferromagnetic type of spin ordering is confirmed under condition of the diamagnetic dilution with Ga, starting from x = 0.8. At x = 0.1, unusual broadening and splitting of the EPR spectrum are found upon cooling; this can be assigned to the effect of thermally activated internal motion with characteristic energy Ea of about 50 meV. The study of nuclear spin-lattice relaxation was performed in the temperature range of 190-390 K. The obtained data support the existence of the internal motion with the same value of Ea . This motion can be attributed to thermally activated re-orientations of the eg electron orbitals of the Mn3+ ions subjected to the Jahn-Teller effect.
Supporting agencies: Работа поддержана грантом РФФИ 02- 02-16219 Программой фундаментальных исследований РАН "Спин-зависимые эффекты в твердых телах и спинтроника" и грантом NSF CREST Project HRD-9805059
About the Authors
V. A. Atsarkin
Institute of Radio Engineering and Electronics RAS
Russian Federation
Russian Federation
125009 Moscow
V. V. Demidov
Institute of Radio Engineering and Electronics RAS
Russian Federation
Russian Federation
125009 Moscow
G. D. Gotovtsev
Institute of Radio Engineering and Electronics RAS
Russian Federation
Russian Federation
125009 Moscow
N. E. Noginova
Institute of Radio Engineering and Electronics RAS; Norfolk State University
Russian Federation
Russian Federation
125009 Moscow; Norfolk, VA 23504, USA
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Review
For citations:
Atsarkin V.A., Demidov V.V., Gotovtsev G.D., Noginova N.E. Effect of diamagnetic dilution on spin dynamics in manganites (in Russian). Magnetic Resonance in Solids. 2004;6(1):1-9.
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