EPR Manganites Activation energy Electrons Lanthanum compounds Manganese compounds
Issue Date:
2006
Publisher:
Journal of Magnetism and Magnetic Materials
Citation:
Volume: 303, Issue: 2 SPEC. ISS.
Abstract:
We studied electron spin resonance (ESR) spectra of La0.7A?0.3MnO3 (A?=Sr, Ba, Pb, and Cd)
perovskites in a large range of temperature, from their Curie temperature to ?500 K. Asymmetrical EPR
signals at temperatures TC < T < Tmin, due to FM correlations, became Lorentzian at T {greater than or
slanted equal to} Tmin, where Tmin is the temperature corresponding to the narrowest ESR linewidth. The
ESR linewidth vs. temperature, ??H(T), in the region T > Tmin well fits to the model of adiabatic hopping
motion of small polarons ?? H ( T ) = ?? H0 + ( a / T ) exp ( - Ea / kB T ), where Ea and kB are the
activation energy and the Boltzmann factor, respectively; ??H0 and a are constants. It is worth noticing that,
in this temperature range, the Lande factor g for the samples is about 2.00, indicating spin-spin interaction
among electrons of Mn3+ and Mn4+ ions playing an important role. ?? 2006 Elsevier B.V. All rights
reserved.
