Anisotropic domains and antiferrodistortive-transition controlled magnetization in epitaxial manganite films on vicinal SrTiO3 substrates

We studied the microstructural evolution and magnetism of ferroelastic La0.9Sr0.1MnO3 (LSMO) epitaxial thin films grown on SrTiO3 (001) substrates with different miscut angles. The substrate miscut angle plays a critical role in controlling the in-plane magnetic anisotropy. The microscopic origin of such magnetic anisotropy is attributed to the formation of anisotropic stripe domains along the surface step terraces. The magnetization in the LSMO films was found to be selectively modulated by the antiferrodistortive phase transition of the SrTiO3 substrate. This phenomenon has been qualitatively explained by a strain modified Stoner-Wohlfarth model. We conclude that the magnetization modulation by the SrTiO3 phase transition depends on h, the ratio of applied magnetic field to the saturation field. Such modulation is only visible with h<1. The established domain microstructure-anisotropy-magnetism correlation in manganite films can be applied to a variety of complex oxide thin films on vicinal substrates.