Microstructure, Magnetic, and Magnetoresistance Properties of La_0.7Sr_0.3MnO₃:CuO Nanocomposite Thin Films

(La_0.7Sr_0.3MnO₃)_0.67:(CuO)_0.33 (LSMO:CuO) nanocomposite thin films were deposited on SrTiO₃ (001), LaAlO₃ (001), and MgO (001) substrates by pulsed laser deposition, and their microstructure as well as magnetic and magnetoresistance properties were investigated. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results show that LSMO:CuO films grow as highly textured self-assembled vertically aligned nanocomposite (VAN), with a systematic domain structure and strain tuning effect based on the substrate type and laser deposition frequency. A record high low-field magnetoresistance (LFMR) value of ∼80% has been achieved in LSMO:CuO grown on LaAlO₃ (001) substrate under high frequency. Detailed analysis indicates that both the strain state and the phase boundary effect play a significant role in governing the overall LFMR behavior.