Abstract
Since the discovery of the anomalous Hall effect (AHE), the anomalous Hall conductivity (AHC) has been thought to be zero when there is no net magnetization. However, the recently found relation between the intrinsic AHE and the Berry curvature predicts other possibilities, such as a large AHC in noncolinear antiferromagnets with no net magnetization but net Berry curvature. Vice versa, the AHE in principle could be tuned to zero, irrespective of a finite magnetization. Here, we experimentally investigate this possibility and demonstrate that the symmetry elements of Heusler magnets can be changed such that the Berry curvature and all the associated properties are switched while leaving the magnetization unaffected. This enables us to tune the AHC from up to with an exceptionally high anomalous Hall angle up to 12%, while keeping the magnetization the same. Our study shows that the AHC can be controlled by selectively changing the Berry curvature distribution, independent of the magnetization.
- Received 3 July 2018
- Revised 25 September 2018
DOI:https://doi.org/10.1103/PhysRevX.8.041045
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Apply a magnetic field perpendicular to an electric current passing through a conductor, and you will generate a voltage transverse to both. This is the well-known Hall effect. When applied to certain magnetic materials, an additional transverse voltage arises, which is known as the anomalous Hall effect. It has long been assumed that in the absence of magnetization, this effect disappears. However, recent research has suggested that this may not be the case. Here, we experimentally show that the anomalous Hall effect can be tuned by controlling a material’s Berry curvature, a property of the electronic band structure that determines topological behavior.
In our experiments, we focus on a class of magnetic crystalline compounds known as Heusler magnets. By changing the chemical composition via a suitable change of atoms or by varying the number of valance electrons, we can easily alter the details of the band structure and hence engineer the Heusler magnet’s Berry curvature while leaving the magnetization unchanged. This lets us tune the anomalous Hall conductivity from to .
Our experiments show, for the first time, that the anomalous Hall effect can be tuned over a large range, which provides solid insight into the origin of this effect and possible applications in spintronic devices that utilize the topological properties of matter.