# Anisotropic spin-density distribution and magnetic anisotropy of strained La$_{1-x}$Sr$_x$MnO$_3$ thin films: Angle-dependent x-ray magnetic circular dichroism

## TL;DR

This study uses angle-dependent x-ray magnetic circular dichroism to reveal how strain influences the anisotropic spin-density distribution and magnetic anisotropy in La$_{1-x}$Sr$_x$MnO$_3$ thin films, clarifying surface orbital occupation effects.

## Contribution

It provides direct experimental evidence of strain-dependent in-plane and out-of-plane spin-density anisotropy in LSMO thin films using XMCD, resolving previous ambiguities from XLD measurements.

## Key findings

- Spin-density distribution anisotropy aligns with magnetic anisotropy.
- Tensile strain induces in-plane spin-density anisotropy.
- Compressive strain induces out-of-plane spin-density anisotropy.

## Abstract

Magnetic anisotropies of ferromagnetic thin films are induced by epitaxial strain from the substrate via strain-induced anisotropy in the orbital magnetic moment and that in the spatial distribution of spin-polarized electrons. However, the preferential orbital occupation in ferromagnetic metallic La$_{1-x}$Sr$_x$MnO$_3$ (LSMO) thin films studied by x-ray linear dichroism (XLD) has always been found out-of-plane for both tensile and compressive epitaxial strain and hence irrespective of the magnetic anisotropy. In order to resolve this mystery, we directly probed the preferential orbital occupation of spin-polarized electrons in LSMO thin films under strain by angle-dependent x-ray magnetic circular dichroism (XMCD). Anisotropy of the spin-density distribution was found to be in-plane for the tensile strain and out-of-plane for the compressive strain, consistent with the observed magnetic anisotropy. The ubiquitous out-of-plane preferential orbital occupation seen by XLD is attributed to the occupation of both spin-up and spin-down out-of-plane orbitals in the surface magnetic dead layer.