Magnetic Domain Structure of La0.7Sr0.3MnO3 thin-films probed at variable temperature with Scanning Electron Microscopy with Polarization Analysis

TL;DR

This study uses SEMPA to directly image the magnetic domain structure of La0.7Sr0.3MnO3 thin films, revealing surface-specific temperature-dependent magnetic behavior and domain characteristics.

Contribution

It demonstrates SEMPA's effectiveness in probing surface magnetic domains and their temperature evolution in La0.7Sr0.3MnO3 films without surface preparation.

Findings

Large four-fold anisotropy with a small uniaxial component

Domain wall width consistent with previous estimates

Surface contrast decreases faster with temperature than bulk magnetization

Abstract

The domain configuration of 50 nm thick La0.7SrMnO3 films has been directly investigated using scanning electron microscopy with polarization analysis (SEMPA), with magnetic contrast obtained without the requirement for prior surface preparation. The large scale domain structure reflects a primarily four-fold anisotropy, with a small uniaxial component, consistent with magneto-optic Kerr effect measurements. We also determine the domain transition profile and find it to be in agreement with previous estimates of the domain wall width in this material. The temperature dependence of the image contrast is investigated and compared to superconducting-quantum interference device magnetometry data. A faster decrease in the SEMPA contrast is revealed, which can be explained by the technique's extreme surface sensitivity, allowing us to selectively probe the surface spin polarization which due to the double exchange mechanism exhibits a distinctly different temperature dependence than the bulk magnetization.