The role of Co substitution in the structural characteristics and magnetic properties of La2CoxNi1-xMnO6 epitaxial film

Abstract

Novel La2CoxNi1-xMnO6 (LCxNMO, x = 0–0.4) thin films were prepared by pulsed laser deposition, and the influences of Co-doping content on the crystallographic structure, chemical structure as well as magnetic property were studied. The AFM and SEM images revealed a uniform film growth and smooth surfaces for all the films. The (HR)XRD analysis and their RSM results testified for the formation of pseudocubic perovskite films epitaxially grown onto LAO(00l) substrate. The in-plane lattice parameter increased with increasing proportion of Co substituting for Ni sites, as expected due their ionic radii differences. In our work, a change of Mn3+ + Ni3+/Co3+ → Mn4+ + Ni2+/Co2+ was found, and the mechanism in the enhancement of the magnetic property was demonstrated. It proposed that the performances of all the films can be enhanced and regulated by controlling the Co-doping content. Among all the films, LC0.2NMO film possessed the maximum Mn4+ ion concentration (80%) and displayed the highest B-site ordering degree. As a consequence, LC0.2NMO was achieved to exhibit a high Curie temperature (278.4 K) and the best saturation magnetization (513.72 emu/cm3), on account of the combined effects of the strong B-site cation ordering and the structural distortion after Co-doping.