Strain-tunable spin filtering and valley splitting coexisting with the anomalous Hall effect in the 2D half-metallic VSe2/VN heterostructure: toward a unified spintronic–valleytronic platform

Abstract

Rapid progress in valleytronics and spintronics is limited by the scarcity of two-dimensional materials that simultaneously provide robust valley splitting and strong spin selectivity. Here we show that a van der Waals heterostructure (VSe₂/VN) built from hexagonal VSe₂ and hexagonal VN addresses this gap. Using first-principles density functional theory, phonon dispersion, ab initio molecular dynamics stability tests, Bader charge analysis, and Wannier-based Berry-curvature calculations, we demonstrate an energetically and dynamically stable heterostructure that exhibits interlayer charge transfer and a work function intermediate between the constituent monolayers. The electronic structure showed a small indirect PBE gap (108.9 meV), with HSE06 indicating a half-metallic tendency; a sizable conduction-band valley splitting (ΔC_KK′ = 22.9 meV for spin-up and ΔC_KK′ = 61.3 meV for spin-down); and pronounced spin asymmetry, where the spin-down channel showed a wide semiconducting gap (0.64 eV) while the spin-up channel was nearly gapless. These features yielded a high zero-strain spin-filter efficiency P = 75.4%, tunable to 82.5% under +4% biaxial tensile strain. The heterostructure also supported non-zero, valley-contrasting Berry curvature, and a large anomalous Hall conductivity (peak σ_xy= 568.33 S cm⁻¹). Importantly, a Monte Carlo derived equation placed the ferromagnetic Curie temperature, T_C = 47.39 K at zero strain, while T_C decreased to 30.68 K at +4% strain, and the magnetic order remained robust to cryogenic temperatures, providing a beneficial tuning knob to balance spin-filter performance with thermal stability in device-relevant regimes. These results identified VSe₂/VN as a practical, strain-tunable platform for integrated valleytronic, spintronic devices, and for exploring anomalous Hall and valley-dependent transport phenomena.