Low-Field Magnetoresistance in 2-2 Composites of La_0.7Sr_0.3MnO₃ and Metal Oxides

Pure La_0.7Sr_0.3MnO₃ (LSMO) exhibits colossal magnetoresistance, making it suitable for high-field applications. We find that the addition of insulating metal oxides in composite films results in low-field magnetoresistance (LFMR), thus expanding the application space for LSMO into the low-field regime. In this work, pure LSMO thin films are compared to composite layered heterostructures of LSMO and either SrO, TiO₂, or ZrO_2, grown on (001) oriented LaAlO₃ and SrTiO₃ substrates via chemical solution deposition. Structural, magnetoelectric, and magnetic transport properties are presented. X-ray diffraction and Raman spectroscopy studies confirm chemical phase purity of all films, (001) oriented growth of pure LSMO, and polycrystalline LSMO heterostructures. Magnetic susceptibility measurements indicate a Curie temperature and metal-insulator transition temperature both near 370K for all samples. This work indicates that the inclusion of insulating metal oxides in heterostructural films is a relatively simple and scalable method for improving LSMO applications at low fields.