Fabrication of La_0.8Na_0.2Mn_1 xCu_xO₃ (x = 0, 0.05) thin films on YSZ substrates via chemical solution deposition

a-Axis oriented La0.8Na0.2MnO3 (LNMO) and La0.8Na0.2Mn0.95CU0.05O3 (LNMCO) films with large magnetoresistance (MR) near room temperature are fabricated via chemical solution deposition on yttrium-stabilized zirconia (YSZ) (100) single crystal substrates. With slight Cu doping, it is found that the growth mode is changed from the layer-by-layer mode of the LNMO film to the island mode of the LNMCO film. The LNMO film exhibits typical transport properties of epitaxial films of manganites. However, the LNMCO film shows transport properties corresponding to polycrystalline films of manganites. The MR value of the LNMCO film at low applied magnetic field is also remarkably enhanced compared with that of the LNMO film below the insulator-metal transition temperature. MR as high as 9% is obtained at a field of 0.05 T at 5 K. The enhanced MR effect for the LNMCO film is attributed to the spin-dependent scattering of polarized electrons at the grain boundaries.