Sublattice-spin-valley-locked Weyl semimetals in van der Waals stacked structures

We propose a universal tight-binding model for realizing three-dimensional (3D) Weyl semimetals (WSMs) in van der Waals (vdW) stacked structures composed of honeycomb lattices. A large intralayer staggered potential (U), combined with a significant difference $(\mathrm{\ensuremath{\Delta}}t)$ in the interlayer vdW interactions between the two honeycomb sublattices, can effectively facilitate the emergence of the WSMs. The relative strengths of the interlayer vdW hoppings between the two sublattices with ${p}_{xy}$ orbitals determine the types of the WSMs formed. In contrast to conventional WSMs, the realized WSMs can exhibit a rare sublattice-spin-valley (SSV) locking, with $100%$ spin and valley polarization. Rich topological phase transitions, spanning five distinct phases, arise from the interplay between spin-orbit coupling ($\ensuremath{\lambda}$), U, and $\mathrm{\ensuremath{\Delta}}\mathrm{t}$. First-principles calculations discover that 3D halogenated arsenene vdW materials are ideal for observing the exotic SSV-locked Fermi arcs, which feature a record-long length. Our research provides a vdW-stacked strategy for engineering unique WSMs, enabling high-performance spintronic and valleytronic applications through spatial control.