55Mn NMR and magnetization studies of La0.67Sr0.33MnO3 thin films

Mn-55 nuclear magnetic resonance and magnetization studies of the series of La0.67Sr0.33MnO3 thin films have been performed at low temperature. Two distinct lines were observed, at 322 MHz and 380 MHz, corresponding to two different phases, the former located at the interface, with localized charges, and the latter corresponding to the film bulk, with itinerant carriers (as it was also found in Ca manganite films). The spin-echo amplitude was measured as a function of a dc magnetic field applied either in the film plane or perpendicular to it. The field dependence of the NMR signal intensity above the effective anisotropy field agrees well with a model of magnetically homogeneous sample. The enhanced magnetic anisotropy estimated for the NMR signal from the interface is consistent with its very small thickness, indicating similar magnetic properties in charge localized and itinerant regions.