Influence of Er doping on La site on lattice effect of low field magnetoresistance of manganite La0.7Ca0.3MnO3.

When La in perovskite (ABO₃) manganite is partially substituted by rare earth element Er, average ionic radius on A site decreases, resulting in influence of internal pressure generated in a lattice on electronic activity energy band overlapped between the d orbit on B site and the p orbit on O site. Manganite polycrystalline samples La_0.7-xEr_xCa_0.3MnO₃(x = 0, 0.1, 0.2) were prepared by solid-state reaction technique. X-ray diffraction spectra, resistance-temperature (R-T) curves and magnetoresistance-temperature (MR-T) curves of the samples were measured. The influence of different substitution of Er for La on low field magnetoresistance effect of the samples was analyzed. Experimental results showed that crystal structure of the samples was cubic structure. Lattice constant d_Mn-Mn, and transition temperature between ferromagnetic state and paramagnetic state T_C of the samples decreased with the increase of Er doping. Tolerance factor t of the samples was less than 1 and Mn-O-Mn bond angle of the samples was less than The samples showed obvious low field magnetoresistance effect in experimental temperature range in 0.25 T magnetic field. [ABSTRACT FROM AUTHOR]