Electron spin resonance studies of Bi0.6Ca(0.4-x)SrxMnO3

The temperature dependent electron spin resonance (ESR) studies were carried out on Bi0.6Ca(0.4-x)SrxMnO3 (0 <= x <= 0.4) . The variation of charge ordering temperature, T-CO, and Neel temperature, T-N, are obtained from plots of double integrated (DI) intensity and linewidth (Delta H) of the ESR signal as a function of temperature. In the temperature range T > T-CO, the sample is in the paramagnetic phase and the magnetic interactions are dominated by ferromagnetic (FM) spin correlations. In the range T-N < T < T-CO, the FM and antiferromagnetic (AFM) correlations coexist. The sample with x=0 has T-CO=313 K and T-N=150 K. With the increase in Sr content from the FM correlations increase resulting in the weakening of the CO and AFM transitions. The CO and the AFM transitions are barely noticed in the sample with x=0.1 indicating the melting of charge-ordered state. The CO transition reappears for x=0.16 at a temperature of similar to 390 K. The growth of high T-CO phases is a nonlinear evolution process with increase in Sr content. (C) 2010 American Institute of Physics. [doi:10.1063/1.3350908]