Domain wall dynamics in ultra thin manganite film

Abstract

Kinetics of magnetization reversal and dynamics of domain walls in thin La0:7Sr0:3MnO3 manganite films are studied by magnetooptic visualization technique. Two types of magnetic domain structure are revealed in 20 nm thin film, namely, the small-scale patched domains with perpendicular magnetization, which are formed after zero field cooling, and wide macro-domains with an in-plane magnetization, which appear as a remnant state after saturation by the field of any orientation. The following magnetization reversal is found to occur via the nucleation and thermoactivated motion of the 1800 domain walls. Strong temperature dependence of dynamic parameters is established near the room temperature. A heating of 10 K above 294 K results in 1.5 reduction of coercivity, in alteration of magnetic permeability, magnetic viscosity and activation volume by order of magnitude. The obtained results could be explained taking into account magnetic after-effects specific for materials with the magnetic ions of transient valence. © 2010 IOP Publishing Ltd.