Thickness dependence of perpendicular magnetic anisotropy in La0.7Sr0.3MnO3La0.7Sr0.3MnO3 films on LaAlO3LaAlO3

We have studied the thickness dependence of magnetic domain patterns of magnetoresistive La0.7Sr0.3MnO3La0.7Sr0.3MnO3 films on LaAlO3LaAlO3 substrates using magnetic force microscopy. Maze-like domain patterns caused by perpendicular magnetic anisotropy were suddenly developed above the film thickness of ∼65nm. This evolvement of magnetic domain pattern was consistent with the magnetic hysteresis data and it can be explained by a simple simulation based on the classical Kittel's model. The critical thickness for the appearance of perpendicular magnetic anisotropy is likely to be determined by a competition between the out-of-plane strain magnetic anisotropy and the in-plane shape anisotropy.