Design strong anomalous Hall effect via spin canting in antiferromagnetic nodal line materials

TL;DR

This paper demonstrates that weak spin canting in antiferromagnetic nodal line materials can induce and enhance a strong anomalous Hall effect, offering a new way to design and control AHE in topological magnetic materials.

Contribution

It reveals that antiferromagnetic nodal line band structures with spin canting can generate strong intrinsic AHE, which was previously overlooked due to symmetry constraints.

Findings

Weak spin canting induces strong AHE in $A$MnBi$_2$ compounds.

Anomalous Hall conductivity increases with canting angle.

Spin canting can be experimentally tuned via doping.

Abstract

The interplay between magnetism and topological electronic structure offers a large freedom to design strong anomalous Hall effect (AHE) materials. A nodal line from band inversion is a typical band structure to generate strong AHE. Whereas, in most collinear antiferromagnets (AFMs), the integration of Berry curvatures on Brillouin zone is forced to zero by the joint $TO$ symmetry, where $T$ and $O$ are time reversal and a space group operation, respectively. Even with inverted band structures, such kind of AFM cannot have AHE. Therefore, so far, AFM nodal line band structures constructed by spin degenerated bands didn't get much attentions in AHE materials. In this work, we illustrate that such kind of band structure indeed provides a promising starting point to generated strong local Berry curvature by perturbations and, therefore, strong intrinsic AHE. In specific AFM compounds of $A$MnBi$_2$($A$=Ca and Yb) with inverted band structure, we found a strong AHE induced by a weak spin canting, and due to nodal line in the band structure the anomalous Hall conductivity keeps growing as the canting angle increases. Since such spin-canting can be adjusted via doping experimentally, it provides another effective strategy to generate and manipulate strong AHE