Doped Electron Localization: Electron Paramagnetic Resonance Probing Of La0.3ca0.7mno3 Compound

The X-band electron paramagnetic resonance (EPR) was studied in the electron-doped ceramic La0.3Ca0.7MnO3. The model fittings of measured temperature dependences of the EPR linewidth and intensity were employed to probe the paramagnetic spin correlations and spin dynamics. These fittings revealed notable ferromagnetic short-range correlations and pure ion-ion spin relaxation in the paramagnetic state of La0.3Ca0.7MnO3. The latter fact supports the local nature of ferromagnetic double exchange coupling in this very case. It is suggested that such character of ferromagnetic exchange interactions results in the localization of carriers and establishing of charge ordered antiferromagnetic insulating ground state. This finding may be considered a strong prerequisite for the electron-hole doping asymmetry observed in the phase diagram of La-Ca manganites. (C) 2011 American Institute of Physics. [doi:10.1063/1.3540309]