Substrate and growth related microstructural and magnetic properties in La_0.67Sr_0.33MnO₃ thin films

Ambient observation of magnetic domain structures by magnetic force microscopy (MFM) in La_0.67Sr_0.33MnO₃ films has not been clearly correlated with stresses induced by kinetic growth processes or the compressive (LaAlO₃) or tensile (SrTiO₃) nature of the film-substrate lattice mismatch. Although domain-like magnetic structures have been seen for some as-grown films and related to substrate-induced stress and film thickness, no magnetic structure has been seen for other films grown under similar conditions on the same pair of substrates. In this study we have grown films over a range of temperatures by pulsed-laser deposition, using the above substrates, to determine the relationship between growth and stress-induced magnetic structures. Results from scanning tunneling, atomic force, and magnetic force microscopies, measurements of temperature-dependent magnetization and structure-dependent coercivity show the relationship between growth and magnetic properties. Maze-like domain structures, with separations between 150 nm and 200 nm, were only observed for the thicker films grown at the highest temperature, 800 °C. Application of an in-plane magnetic field converted these domain structures to stripe-like domains whose spacing and out of plane component decreased as the field was increased.