Low-field magnetoresistance of La0.7Ca0.3MnO3 perovskite synthesized by reactive milling method

Nanocrystalline, granular samples of La0.7Ca0.3MnO3 (LCMO) were synthesized by reactive milling method and annealed at various temperatures. Effect of grain size on the low-field magnetoresistance (LFMR) has been investigated. Based upon a phenomenological model taking into account the spin-polarized transport across grain boundaries, we explained magnetic field dependence of magnetoresistance in LCMO samples. The contribution to the magnetoresistance coming from spin-polarized tunneling was separated out from the intergranular contribution. The fitted results showed that the temperature dependence of the LFMR displays a Curie–Weiss law-like behavior.