Semiconductor-to-metal transitions in spin-valve-like van der Waals heterostructures based on buckled honeycombs

Abstract We propose novel spin-valve-like van der Waals heterostructures, in where one nonmagnetic buckled honeycomb monolayer intercalates two insulating ferromagnets. By switching the relative orientation of magnetic moments in two ferromagnets from antiparallel to parallel arrangement, semiconductor-to-metal transition yields owing to a strong magnetic proximity effect. Based on first-principles calculations, we have tested the feasibility of this model. Twelve heterostructures are investigated and seven in them show the desired semiconductor-to-metal transition. Especially, the CrI3/Ge/CrI3 heterostructure exhibits the biggest opening gap on the value of 0.31 eV among all heterostructures. Using a simple tight-binding model and the perturbation theory, we have revealed that such magnetic-order-dependent semiconductor-to-metal transition originates from the spin splitting induced by the strong magnetic proximity effect. We find an appreciable strength of magnetic proximity is crucial for achieving the semiconductor-to-metal transition, via closing the bandgap only for the parallel arrangement but remaining the antiparallel arrangement to be semiconductive. The presented heterostructures enable reversible and nonvolatile control of semiconductor-to-metal transition and are of giant potential in low-consumption and nonvolatile logic and memory devices.