Large low-field magnetoresistance observed in heterostructure La0.7Ca0.3MnO3/Gd0.7Ca0.3MnO3 superlattices

La0.7Ca0.3MnO3(LCMO)/Gd0.7Ca0.3MnO3(GCMO) multilayers have been prepared by pulsed laser deposition. High-resolution transmission electron micrographs demonstrate that perfect hetero-epitaxial growth has been achieved in the LCMO/GCMO superlattices with strains. In the superlattices, the resistivity-peak temperature decreases with reducing the thickness of the LCMO layers. Large low field magnetoresistance (LFMR) of Δρ/ρH=278% is obtained at 78.5 K in a LCMO/GCMO superlattice when a magnetic field swept within ±3100 Oe. This result suggests that the interface strains between LCMO and GCMO layers may have influences on the magnetic transport properties and a suitable film structure could be used to increase the LFMR.