Electron spin resonance study of the Ba-doping manganite Nd_0.5Sr_0.5MnO₃

We have performed magnetization measurements and electron spin resonance (ESR) on polycrystalline manganites of Nd_0.5Sr_0.5 - xBa_xMnO_3 (x = 0.1). Phase separation and phase transitions are observed from the susceptibility and the ESR spectra data. Between 260 K (\sim T_\rm C) and 185 K (\sim T_\rm N), the system coexists of the paramagnetic phase and the ferromagnetic (FM) phase. Between 185 K and 140 K, the system coexists of the FM phase and the antiferromagnetic (AFM) phase. These results indicate that the system has a very complex magnetic state due to the origin of the instability stemming from manganite Nd_0.5Sr_0.4Ba_0.1MnO_3 by partially substituting the larger Ba^2 + ions for the smaller Sr^2 + ions.