Ab-initio exploration of Gd monolayer interfaced with WSe$_2$: from electronic and magnetic properties to the anomalous Hall effect

TL;DR

This study investigates magnetism and topological transport in a Gd/WSe$_2$ 2D heterostructure using ab initio DFT+U calculations and Berry-curvature analysis. It demonstrates that a ferromagnetic metallic interface emerges due to Gd–WSe$_2$ hybridization, yielding a large out-of-plane magnetic moment around ${7.36~ extmu_B}$ and SOC-driven band splitting that produces substantial anomalous Hall conductivity. The AHC is shown to be highly tunable by modest in-plane lattice strain and by adjusting the interlayer spacing, with values ranging across sign and magnitude depending on structural parameters. These results highlight a viable route to engineer 2D spintronic devices via magnetic proximity and controlled structural modification.

Abstract

Heterostructures involving transition metal dichalcogenides (TMDs) have attracted significant research interest due to the richness and versatility of the underlying physical phenomena. In this work, we investigate a heterostructure consisting of a rare-earth material, specifically a Gd monolayer, interfaced with WSe$_2$. We explore its electronic structure, magnetic properties, and transport behavior, with particular emphasis on the emergence of the anomalous Hall effect (AHE). Both Gd and W are heavy elements, providing strong spin-orbit coupling (SOC), which plays a crucial role in triggering the AHE. The combination of strong SOC and inversion symmetry breaking leads to pronounced asymmetries between the $Γ-K$ and $Γ-K^\prime$ directions in the Brillouin zone. Our calculations reveal a substantial anomalous Hall conductivity (AHC) at the ferromagnetic interface, primarily originating from numerous avoided crossings involving the d-states of both Gd and W near the Fermi level. Moreover, we demonstrate that the AHC is highly tunable, either by adjusting the in-plane lattice constant or by reducing the separation between Gd and WSe$_2$.

Figures (6)

• Figure 1: Crystal structure of Gd/WSe$_{2}$. (a) and (b) respectively show the side and top views.
• Figure 2: (color online) Calculated electronic structure for Gd/WSe$_2$. (a),(c) Calculated band structures both in the scalar relativistic and fully relativistic cases, for $a = 3.43~\text{\AA}$, U$= 0~\text{eV}$ and $a = 3.39~\text{\AA}$, U$= 3.5~\text{eV}$, respectively. The red and blue lines represent respectively the spin up and spin down of the scalar relativistic calculation, while the black line represents the fully relativistic bands. (b),(d) Calculated scalar projected density of states
• Figure 3: (color online) Calculated electronic structure, for Gd/WSe$_2$. (a),(c) Calculated Band structure assuming a U of $3.548~$eV both in the scalar relativistic and fully relativistic cases for respectively $a=3.32~\mathrm{\AA}$ and $a=3.44~\mathrm{\AA}$. The red and blue lines represent respectively the spin up and spin down of the scalar relativistic calculation, while the black line represents the fully relativistic bands. (b),(d) Calculated scalar projected density of states
• Figure 4: Anomalous Hall conductivity as function of the Fermi level for $a=3.32~\mathrm{\AA}$, $a=3.39~\mathrm{\AA}$, $a=3.44~\mathrm{\AA}$ respectivly in red, blue and green lines.
• Figure 5: Anomalous Hall conductivity at the Fermi level as a function of the lattice parameter.