Resonance dc phenomena in manganite thin films

The resonance spin rectification (RSR) and resonance magnetoresistance (RMR) have been studied on La2/3Sr1/3MnO3 epitaxial thin films in the temperature range of 300 - 365 K, including the Curie point (T-C). The RSR effect is found to be caused by anisotropic magnetoresistance under conditions of the magnetic-resonance microwave pumping; it decreases upon heating and disappears at T-C. Unlike that, the RMR is maximal at T-C and shows clear correlation with the colossal magnetoresistance (CMR) of the material under study. The interpretation implies decreasing of the sample magnetization due to resonance saturation, thus leading to an increase in electric resistivity in terms of the CMR mechanism. Quantitative agreement is demonstrated between the experimental RMR data and theory accounting for Bloch-type relaxation in the vicinity of the phase transition.