ESR study of La 1– x Pb x MnO 3 (0.1 ≤ x ≤ 0.5) perovskites

Electron spin resonance (ESR) spectra of La 1– x Pb x MnO 3 (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, Δ H ( T ), for the samples was fitted to the one‐phonon process, Δ 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 tem‐ perature 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. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)