Electron spin resonance study of colossal magnetoresistive materials la_(0.7)Ba_(0.3)Mn_(1-x)Fe_xO_3 (x=0.08-0.2)

摘要

Electron spin resonance (ESR) was carried out on the La _(0.7)Ba_(0.3)Mn_(1-x)Fe_xO_3 (x=0.08-0.2) compounds over the temperature range of 100-300 K. We observed that the temperature dependence of the EPR spectra has a phase separation phenomenon below Tc for x=0.08-0.15 samples. Phase transition and temperature dependence of ESR, g_(eff) value, linewidth, and intensity were determined. The g-value increases gradually with decrease in temperature in the paramagnetic state. The activation energies obtained from the temperature dependence of resonance intensity and linewidth are smaller in the Fe-doped sample. The ferromagnetic spin correlations would be significantly weakened by partially substituting the Mn with Fe.