Large Low-Field Magnetoresistance Observed in Polycrystalline La_(0.7)Ca_(0.3)MnO_(3) Films

Large low-field magnetoresistance(LFMR)of∆p/pH=40%is obtained at 163 K within±3000 Oe in a polycrystalline La_(0.7)Ca_(0.3)MnO_(3)(LCMO)films prepared by pulsed laser deposition.The ratio∆p/pH increases almost linearly with H in the measuring magnetic field range and the peak of LFMR ratios is observed near the resistivity peak temperature,which is different from the observation of spin-polarized intergrain tunnels.This experiment suggests that grain boundaries have large influences on the LFMR.The results indicate that a suitable film process can be used to increase the LFMR of LCMO films.