ESR study of La1-xPbxMnO3 (0.1 ≤ x ≤ 0.5) perovskites

Electron spin resonance (ESR) spectra of La1-xPbxMnO3 (0.1 <= x <= 0.5) compounds were recorded at different temperatures. Asymmetrical and distored resonance signals due to ferromagnetic correlations at temperatures T < T-min became Lorentzian at T > T-min, where T-min is the temperature corresponding to the narrowest ESR linewidth. The ESR linewidth with respect to temperature, Delta H(T), for the samples was fitted to the one-phonon process, Delta H(T) = A + BT. We found that B decreased from 5.45 Oe/K for x = 0.1 to 4.61 Oe/K for x = 0.5, indicating the decrease of lattice distortions with the Pb addition. The temperature dependence of the ESR intensity, I(T), for the samples was described well to an expression of I(T) = I-0 exp (E-a/k(B)T). In the high-temperature region, 1/I(T) obeyed the Curie-Weiss law. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.