Effect of Nd doping on the electrical transport properties of La0.67Ca0.33MnO3 thin films

Nd-doped La0.67Ca0.33MnO3 (La0.67-xNdxCa0.33MnO3) gel films were fabricated on Si (00l) and LaAlO3 (00l) substrates using sol–gel method and acetylacetone as chelating agent. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron (XPS) were used to characterize the structure, composition, and morphology of the films. The electrical transport properties were measured on a physical property measurement system (PPMS) under a relatively low external magnetic field (1 T). Results show that the La0.67-xNdxCa0.33MnO3 films present to be randomly oriented on Si (00l) substrate, but grow epitaxially on LaAlO3 (00l) substrate. Both the magnetoresistance effect and saturation magnetization of the La0.67-xNdxCa0.33MnO3 films are significantly enhanced by Nd doping, although the metal–insulator transition temperature (TIM) decreases. The electrical transport properties of films deposited on Si (00l) and LaAlO3 (00l) substrate are almost same, viz. increases firstly and then decreases with the increase of Nd doping content. When the Nd doping content x = 0.35, the magnetoresistance change rate reaches the maximum value, which is 24.8% and 86.9% of that of the film deposited on Si (00l) and LaAlO3 (00l) substrate, respectively. However, the saturation magnetization reaches the highest level at the Nd content x = 0.15, viz. 520 and 1058 emu/cm3 at 50 K for the films deposited on Si (00 l) and LaAlO3 (00 l) substrate.