Tailoring magnetic anisotropy in epitaxial half metallic La0.7Sr0.3MnO3 thin films

TL;DR

This study investigates how the magnetic anisotropy of La0.7Sr0.3MnO3 thin films can be tailored by substrate orientation and film morphology, revealing the influence of step edges and film thickness on magnetic properties.

Contribution

It demonstrates the control of magnetic anisotropy in LSMO films through substrate surface orientation and morphology, highlighting the role of step edges and film thickness in anisotropy strength.

Findings

Uniaxial anisotropy depends on film morphology and substrate orientation.

Step edges induce uniaxial anisotropy aligned with step direction.

Anisotropy strength increases with film thickness, up to 120 nm.

Abstract

We present a detailed study on the magnetic properties, including anisotropy, reversal fields, and magnetization reversal processes, of well characterized half-metallic epitaxial La0.7Sr0.3MnO3 (LSMO) thin films grown onto SrTiO3 (STO) substrates with three different surface orientations, i.e. (001), (110) and (1-18). The latter shows step edges oriented parallel to the [110] (in-plane) crystallographic direction. Room temperature high resolution vectorial Kerr magnetometry measurements have been performed at different applied magnetic field directions in the whole angular range. In general, the magnetic properties of the LSMO films can be interpreted with just the uniaxial term with the anisotropy axis given by the film morphology, whereas the strength of this anisotropy depends on both structure and film thickness. In particular, LSMO films grown on nominally flat (110)-oriented STO substrates presents a well defined uniaxial anisotropy originated from the existence of elongated in-plane [001]-oriented structures, whereas LSMO films grown on nominally flat (001)-oriented STO substrates show a weak uniaxial magnetic anisotropy with the easy axis direction aligned parallel to residual substrate step edges. Elongated structures are also found for LSMO films grown on vicinal STO(001) substrates. These films present a well-defined uniaxial magnetic anisotropy with the easy axis lying along the step edges and its strength increases with the LSMO thickness. It is remarkable that this step-induced uniaxial anisotropy has been found for LSMO films up to 120 nm thickness. Our results are promising for engineering novel half-metallic magnetic devices that exploit tailored magnetic anisotropy.