Tunable linear and nonlinear anomalous Hall transport in two-dimensional CrPS$_{4}$

TL;DR

This work tackles how intrinsic linear and nonlinear anomalous Hall transport can be realized and controlled in 2D CrPS$_{4}$ with layer-dependent magnetism. Using first-principles DFT with Wannierization, it computes Berry curvature and Berry-connection polarizability to evaluate $ \\sigma_{xy}$ and $ \\chi_{yxx}$ for monolayer and bilayer CrPS$_{4}$, including layer-resolved and gate-tunable effects. Key findings show that monolayer CrPS$_{4}$ exhibits a sizable intrinsic linear AHE that depends on magnetization direction, while bilayer CrPS$_{4}$ hosts a large intrinsic nonlinear AHE due to BCP near gapped Dirac points and supports a layer Hall effect under gating; an in-plane magnetic field can also induce a sizable planar AHE in the bilayer. These results reveal rich, tunable Hall transport in a robust 2D vdW magnet, offering a platform for oxide-free electronic and spintronic devices and for probing band-geometric quantities in 2D magnets.

Abstract

Few-layer CrPS$_{4}$ is a two-dimensional (2D) magnetic material with excellent stability in ambient environment, which attracted significant interest in recent research. Here, via first-principles calculations, we show that 2D CrPS$_{4}$ hosts a variety of anomalous Hall transport phenomena, owing to its layer-dependent magnetism and symmetry character. Monolayer CrPS$_{4}$ can display a sizable linear anomalous Hall effect, while its nonlinear anomalous Hall response is forbidden. In contrast, bilayer CrPS$_{4}$ can produce pronounced intrinsic nonlinear anomalous Hall response from Berry-connection polarizability, in the absence of linear anomalous Hall effect. We clarify that the large peaks in these responses originate from gapped Dirac points in the band structure. Furthermore, we show that linear anomalous Hall effect can be induced and controlled in bilayer CrPS$_{4}$ by gate electric field or in-plane magnetic field, which break the spacetime inversion symmetry. Our findings unveil the interesting layer-dependent Hall transport physics in 2D CrPS$_{4}$ magnets, suggesting its potential in electronic and spintronic device applications.

Figures (8)

• Figure 1: (a) Top view of a CrPS$_4$ layer. The black rectangle marks the conventional cell. (b) Lattice structure of bulk CrPS$_4$. It has a $A$-type AFM ground state. The local moments are in the out-of-plane direction, as indicated by the red arrows in the figure.
• Figure 2: (a) Brillouin zone and (b) calculated band structure for bulk CrPS$_4$.
• Figure 3: (a) Lattice structure of monolayer CrPS$_4$, which has FM ordering with out-of-plane magnetization. (b) Brillouin zone of the monolayer. (c) Band structure for monolayer CrPS$_4$ in the FM ground state.
• Figure 4: (a) Calculated intrinsic anomalous Hall conductivity for monolayer CrPS$_4$ as a function of chemical potential. (b) Distribution of Berry curvature for states below $\mu=-0.32$ eV. (c) The hot spots in (b) correspond to the gapped Dirac points in band structure. The red arrow indicates one point. The other one is related to this one by inversion symmetry. (d) The result of intrinsic anomalous Hall conductivity when the magnetization is rotated to be along the $x$ direction.
• Figure 5: (a) Lattice structure of bilayer CrPS$_4$, which has $A$-type AFM ground state. (b) Calculated band structure for bilayer CrPS$_4$ in AFM ground state.