Giant room temperature anomalous Hall effect and magnetically tuned topology in the ferromagnetic Weyl semimetal Co2MnAl

TL;DR

This study demonstrates that in ferromagnetic Weyl semimetal Co2MnAl, a weak magnetic field can induce a giant, tunable anomalous Hall effect at room temperature by manipulating the material's topological features, advancing spintronic applications.

Contribution

It introduces a method to control topological band structures via magnetic fields at room temperature, enabling practical manipulation of anomalous Hall effects in magnetic topological materials.

Findings

Giant anomalous Hall effect observed at room temperature.

Hall angle reaches a record 21% at room temperature.

Proposed material design to generate large Hall effects without Weyl points.

Abstract

Weyl semimetals (WSM) have been extensively studied due to their exotic properties such as topological surface states and anomalous transport phenomena. Their band structure topology is usually predetermined by material parameters and can hardly be manipulated once the material is formed. Their unique transport properties appear usually at very low temperature, which sets challenges for practical device applications. In this work, we demonstrate a way to modify the band topology via a weak magnetic field in a ferromagnetic topological semimetal, Co2MnAl, at room temperature. We observe a tunable, giant anomalous Hall effect, which is induced by the transition between Weyl points and nodal rings as rotating the magnetization axis. The anomalous Hall conductivity is as large as that of a 3D quantum anomalous Hall effect (QAHE), with the Hall angle reaching a record value (21%) at the room temperature among magnetic conductors. Furthermore, we propose a material recipe to generate the giant anomalous Hall effect by gaping nodal rings without requiring the existence of Weyl points. Our work reveals an ideal intrinsically magnetic platform to explore the interplay between magnetic dynamics and topological physics for the development of a new generation of spintronic devices.