Spin-reorientation driven topological Hall effect in Fe4GeTe2

TL;DR

This study reveals a large topological Hall effect in Fe4GeTe2 driven by spin-reorientation transitions, highlighting the interplay of magnetic anisotropies and non-coplanar spin textures in a nearly room-temperature van der Waals ferromagnet.

Contribution

It demonstrates the angle-dependent and thickness-sensitive topological Hall effect in Fe4GeTe2 linked to spin textures and phase transitions, a novel insight into its magnetic properties.

Findings

Large THE observed at in-plane magnetic field orientation.

THE persists over a wide temperature range around SRT.

Thickness-dependent THE linked to reentrant Lifshitz transition.

Abstract

Iron-based van der Waals (vdW) ferromagnets with relatively high ordering temperatures are a current research focus due to their significance in fundamental physics and potential applications in spintronics. Competing magnetic interactions and anisotropies can give rise to nontrivial spin textures in these materials, resulting in novel topological features. Fe4GeTe2 (F4GT) is a nearly room-temperature vdW ferromagnet, well known for hosting a spin-reorientation transition (SRT) arising from the interplay of perpendicular magnetic anisotropy (PMA) and shape anisotropy. In this work, we investigate the angle-dependent magneto-transport properties of F4GT single crystals. We report a large topological Hall effect (THE) in a multi-layer F4GT originating from the SRT-driven non-coplanar spin textures. The THE appears at the in-plane orientation of the external magnetic field and persists over a wide range of temperatures around SRT. Additionally, we find a thickness-sensitive THE signal for the c axis orientation of the magnetic field at a low-temperature regime which is associated with a reentrant Lifshitz transition.