Intrinsic anomalous Hall effect under anisotropic magnetic dipole versus conventional magnetic dipole

TL;DR

This paper compares the intrinsic anomalous Hall effect in ferromagnetic dipole and anisotropic magnetic dipole systems, revealing differences in microscopic mechanisms and potential for giant effects in antiferromagnets.

Contribution

It introduces a theoretical analysis of the anomalous Hall effect in anisotropic magnetic dipole systems, highlighting differences from ferromagnetic systems and implications for antiferromagnetic materials.

Findings

Similar magnitude of anomalous Hall effect in both systems

Smaller magnetization in anisotropic magnetic dipole system

Enhanced effect with weaker spin-orbit coupling

Abstract

We theoretically investigate the intrinsic anomalous Hall effect in two magnetically ordered systems: One is the ferromagnetic dipole system, and the other is the anisotropic magnetic dipole system, the latter of which has been proposed as a microscopic indicator of the anomalous Hall effect in antiferromagnets with the negligibly small magnetization. We show their similarity and difference in the anomalous Hall effect by analyzing the fundamental tight-binding model on a two-dimensional square lattice. We find that the magnitudes of the anomalous Hall effect in the two systems are similar to each other, while the magnetization in the anisotropic magnetic dipole system is much smaller than that in the ferromagnetic dipole system; this indicates that the microscopic mechanisms are different from each other. We show that such a difference appears in the momentum-resolved Berry curvature resulting from the different types of magnetic order parameters. We also show that the anomalous Hall effect in the anisotropic magnetic dipole system is enhanced when the magnitude of the spin-orbit coupling is smaller than that of the magnetic mean field. Our results provide a possibility of the giant anomalous Hall effect in collinear and coplanar antiferromagnetic systems with the anisotropic magnetic dipole.