Stable hump-like Hall effect and non-coplanar spin textures in SrRuO$_3$ ultrathin film

TL;DR

This study reveals a stable hump-like Hall effect in SrRuO$_3$ ultrathin films caused by atomic surface rumplings that induce chiral spin textures, with implications for understanding magnetic properties in two-dimensional ferromagnetic oxides.

Contribution

It demonstrates the atomic-level structural origin of stable non-coplanar spin textures and the resulting Hall effect in ultrathin SrRuO$_3$ films, combining experimental and theoretical analysis.

Findings

Hump-like Hall effect is extremely stable under tilted magnetic fields.

Atomic surface rumplings enhance Dzyaloshinskii-Moriya interaction.

Temperature-dependent X-ray correlates spin textures with Hall effect features.

Abstract

We observed a hump-like feature in Hall effects of SrRuO$_3$ ultrathin films, and systematically investigated it with controlling thicknesses, temperatures and magnetic fields. The hump-like feature is extremely stable, even surviving as a magnetic field is tilted by as much as 85$^\circ$. Based on the atomic-level structural analysis of a SrRuO$_3$ ultrathin film with a theoretical calculation, we reveal that atomic rumplings at the thin-film surface enhance Dzyaloshinskii-Moriya interaction, which can generate stable chiral spin textures and a hump-like Hall effect. Moreover, temperature dependent resonant X-ray measurements at Ru L-edge under a magnetic field showed that the intensity modulation of unexpected peaks was correlated with the hump region in the Hall effect. We verify that the two-dimensional property of ultrathin films generates stable non-coplanar spin textures having a magnetic order in a ferromagnetic oxide material.