Effect of Film Thickness in Electrical Resistivity and Magnetic Properties of Nd0.7Sr0.3MnO3 Thin Films

Abstract

Nd0.7Sr0.3MnO3 thin films of different thicknesses were deposited on (001)-MgO substrate by using a radio frequency-magnetron sputtering system. These films were divided into two batches and were post-annealed separately in an air and oxygen environment, respectively, at 700 °C. Analysis of X-ray diffraction patterns shows that these films crystallise in cubic structure with a typical lattice constant a = 3.847 Ȧ and it expands with increase in film thickness. Both air- and oxygen-annealed films exhibit ferromagnetic transition and the transition temperature gradually rises as the film thickness is increased. Magnetisation loops recorded at 50 K show that all the prepared thin films show ferromagnetic behaviour with a maximum saturation magnetisation value (3.6 μB) comparable to that of bulk sample. The anisotropy constant (K) estimated from the analysis of initial magnetisation curve is found to decrease with increase in film thickness. Metal-insulator transition has been observed and the resistivity data in the insulating region were analysed based on variable range hopping model.