Spin dynamics, electrical and magnetic properties of (La0.5Pr0.5)(0.7)Pb0.3Mn1-xCuxO3 (x=0, 0.02) perovskites
T.L. Phan N.D. Tho M.H. Phan N.D. Ha N. Chau S.C. Yu Magnetization, resistivity, and electron spin resonance (ESR) measurements were carried out to investigate spin dynamics, electrical and magnetic properties of (La0.5Pr0.5)(0.7)Pb0.3Mn1-xCuxO3 (x = 0, 0.02) perovskites. It was found that with Cu addition the Curie temperature decreased from 326 K for x = 0 to 300 K for x = 0.02 composition. The x = 0 sample underwent a metallic-insulator transition at similar to 130 K, whereas the x = 0.02 sample with higher resistivity exhibited ail insulating behavior as a whole. It was furthermore found that asymmetrical ESR signals at low temperatures became Lorentzian at high temperatures above T-min. The temperature dependence of the linewidth, Delta H(T), at T > T-min fits well to the one-phonon model, Delta H(T) = AT + B. The activation energy E, determined from the ESR intensity with respect to temperature, are 0.16 and 0.14 eV for x = 0 and 0.02 compositions, respectively....