Angular dependence of Hall effect and magnetoresistance in SrRuO$_3$-SrIrO$_3$ heterostructures

TL;DR

This study explores the electronic, magnetic, and topological properties of SrRuO$_3$-SrIrO$_3$ heterostructures, revealing interface-induced electronic reconstruction, magnetic anisotropy, and potential skyrmion formation through combined experimental and theoretical analysis.

Contribution

It presents the synthesis and detailed investigation of SrRuO$_3$-SrIrO$_3$ multilayers, uncovering interface-driven electronic and magnetic phenomena, including flat bands, anisotropic magnetoresistance, and indications of non-trivial spin textures.

Findings

Emergence of flat Ru-4d$_{xz}$ bands near interfaces.

Magnetic easy axis tilted by 20° at low fields, rotating with field strength.

Additional Hall effect features suggest formation of non-trivial spin structures.

Abstract

Perovskite SrRuO$_3$ is a prototypical itinerant ferromagnet which allows interface engineering of its electronic and magnetic properties. We report synthesis and investigation of atomically flat artificial multilayers of SrRuO$_3$ with the spin-orbit semimetal SrIrO$_3$ in combination with band-structure calculations with a Hubbard $U$ term and topological analysis. They reveal an electronic reconstruction and emergence of flat Ru-4d$_{xz}$ bands near the interface, ferromagnetic interlayer coupling and negative Berry-curvature contribution to the anomalous Hall effect. We analyze the Hall effect and magnetoresistance measurements as a function of the field angle from out of plane towards in-plane orientation (either parallel or perpendicular to the current direction) by a two-channel model. The magnetic easy direction is tilted by about $20^\circ$ from the sample normal for low magnetic fields, rotating towards the out-of-plane direction by increasing fields. Fully strained epitaxial growth enables a strong anisotropy of magnetoresistance. An additional Hall effect contribution, not accounted for by the two-channel model is compatible with stable skyrmions only up to a critical angle of roughly $45^\circ$ from the sample normal. Within about $20^\circ$ from the thin film plane an additional peak-like contribution to the Hall effect suggests the formation of a non-trivial spin structure.