Room temperature observation of the anomalous in-plane Hall effect in epitaxial thin films of a Weyl ferromagnet

TL;DR

This study demonstrates the observation of the anomalous in-plane Hall effect at room temperature in epitaxial thin films of a Weyl ferromagnet, combining experimental measurements and theoretical insights to enable potential technological applications.

Contribution

The paper reports the first experimental demonstration of room-temperature anomalous in-plane Hall effect in a topological Weyl ferromagnet, using molecular beam epitaxy and heterostructure engineering.

Findings

Anomalous IPHE observed at room temperature in Fe$_3$Sn films.

Enhancement of IPHE through magnetic stray fields in heterostructures.

Theoretical calculations confirm topological Weyl points induce the effect.

Abstract

Topologically nontrivial electronic states can give rise to novel anomalous Hall effects. The potential appearance of these effects at room temperature holds promise for their application in magnetic sensing, spintronics, and energy harvesting technology. The anomalous in-plane Hall effect (IPHE) is predicted to arise in topological magnetic materials when an external magnetic field is applied within the sample plane. Because of stringent symmetry requirements, the conclusive detection of the anomalous IPHE induced by topological electronic states remains challenging, and the study of anomalous Hall effects is often confined to cryogenic conditions. Combining molecular beam epitaxy of the kagome metal Fe$_3$Sn with measurements of the electric Hall effect and theoretical calculations, we propose and experimentally demonstrate that the interplay of the kagome lattice motif with spin-orbit coupling and canted ferromagnetism with large exchange interactions gives rise to the anomalous IPHE at room temperature that is induced by topological Weyl points in the electronic band structure. Synthesizing a topological heterostructure including layers of Fe$_3$Sn and ferromagnetic CoFeB, we further show the enhancement of the anomalous IPHE through the magnetic stray field of the CoFeB layer. Our work establishes a design paradigm for topological magnets and heterostructures to discover and control novel anomalous Hall effects toward their use in technological applications.