Effects of quenched disorder on Griffiths phase and EPR line width in La0.67-2xNd2xCa0.33-xSrxMnO3 manganites

Abstract

It is widely accepted that there is Griffiths phase (GP) present in the paramagnetic phase in doped manganites. We studied the effect of quenched disorder on the region of GP in connection with the temperature dependence of the line width (Delta H) of the electron paramagnetic resonance (EPR) in La0.67-2xNd2xCa0.33-xSrxMnO3 (x = 0, 0.1, 0.15, 0.2 and 0.25). With this approach it is found that Delta H(T), the minimum in the line width (Delta H-min) and T-min are reproduced. With increasing values of the quenched disorder the values of Delta H-min are found to increase. A numerical relation that correlates the temperature range in which GP exists and the cation size disorder is obtained and found to be in agreement with some reported data. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim