ESR study of Sr‐doped LaCoO3 cobaltites

Abstract

AbstractThe electron spin resonance (ESR) method was used to investigate the internal spin dynamics of La1–xSrxCoO3 (x = 0.1, 0.2, 0.3) compounds in the temperature range 170 to ∼500 K. ESR spectra of the samples over the whole temperature range studied could be divided into three regions corresponding to different linewidths. This is due to the presence of an anisotropic field arising from ferromagnetic clusters. This is similar to manganite perovskites. The peak‐to‐peak ESR linewidth vs. temperature, ΔHpp(T), for the samples has a minimum value at a temperature Tmin (in this case Tmin ≈ 1.7TC, whereas Tmin ≈ 1.1TC for manganites). Asymmetric Lorentzian ESR spectra at temperatures T < Tmin become Gaussian at T > Tmin. ESR signals of La1–xSrxCoO3 cobaltites are thermally damped out at ∼460 K, this value being much lower than that for manganite compounds. The explanation of the experimental ΔHpp(T) data in the T > Tmin regime is based on the one‐phonon process and adiabatic hopping motion of small polarons. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)