Uniaxial contribution to the magnetic anisotropy of La0.67Sr0.33MnO3 thin films induced by orthorhombic crystal structure

TL;DR

This study reveals that the orthorhombic crystal structure in La0.67Sr0.33MnO3 thin films induces a uniaxial magnetic anisotropy, likely due to oxygen octahedra rotations affecting magnetic coupling, advancing understanding of magnetocrystalline anisotropy.

Contribution

It demonstrates that orthorhombic structure causes uniaxial magnetic anisotropy in LSMO films, independent of strain differences, highlighting the role of oxygen octahedra rotations.

Findings

Uniaxial anisotropy linked to orthorhombic structure.

Strain mismatch does not explain anisotropy.

Oxygen octahedra rotations influence magnetic coupling.

Abstract

La0.67Sr0.33MnO3 (LSMO) thin films under compressive strain have an orthorhombic symmetry with (1-10)o and (001)o in-plane orientations. (The subscript o denotes the orthorhombic symmetry.) Here, we grew LSMO on cubic (LaAlO3)0.3-(Sr2AlTaO6)0.7 (LSAT) substrates and observed a uniaxial contribution to the magnetic anisotropy which is related to the orthorhombic crystal structure. Since the lattice mismatch is equal in the two directions, the general understanding of anisotropy in LSMO, which relates the uniaxial anisotropy to differences in strain, cannot explain the results. These findings suggest that the oxygen octahedra rotations associated with the orthorhombic structure, possibly resulting in different Mn-O-Mn bond angles and therefore a change in magnetic coupling between the [1-10]o and [001]o directions, determine the anisotropy. We expect these findings to lead to a better understanding of the microscopic origin of the magnetocrystalline anisotropy in LSMO.