Angular dependence of low field magnetoresistance in manganite bicrystalline films

G. ALEJANDRO,L. B. STEREN , J.C. ROJAS SANCHEZ, N. , M. GRANADA , H. PASTORIZA, D. VEGA, B. ALASCIO

Chile

Workshop; Latin American Workshop on Magnetism, Magnetic Materiales and their Applications; 2005

LAW3M

The ferromagnetic manganites, in addition to the colossal magnetoresistance (CMR) near the Curie point, exhibit at low temperatures an extrinsic low field magnetoresistance (LFMR) that arises from scattering at the grain boundaries. The choice of studying manganite films deposited on bicrystalline substrates has the main advantage of isolating a unique artificial grain boundary (AGB). Here we report LFMR measurements performed on La0:75Sr0:25MnO3 films sputtered on SrTiO3 bicrystalline substrates. A Wheatstone bridge of micrometric track width was patterned by electron lithography, and the angular variation of the LFMR was investigated by recording the resistivity of the film at different angles between the AGB and the magnetic field. We have observed that the field dependence of the LFMR strongly varies with this angle, though the LFMR magnitude remains almost constant. X-ray diffraction measurements, ferromagnetic resonance, and dc-magnetization experiments contributing to the characterization of the samples complete this study.a0:75Sr0:25MnO3 films sputtered on SrTiO3 bicrystalline substrates. A Wheatstone bridge of micrometric track width was patterned by electron lithography, and the angular variation of the LFMR was investigated by recording the resistivity of the film at different angles between the AGB and the magnetic field. We have observed that the field dependence of the LFMR strongly varies with this angle, though the LFMR magnitude remains almost constant. X-ray diffraction measurements, ferromagnetic resonance, and dc-magnetization experiments contributing to the characterization of the samples complete this study.