Valley polarization, magnetic anisotropy and band alignment engineering in two-dimensional 2H-VTe2/1T-FeCl2 van der Waals heterostructures

Abstract

The effects of stacking configurations, biaxial strain, and layer distance on the valley polarization and band alignment of 2H-VTe₂/1T-FeCl₂ van der Waals heterostructures are investigated through the first-principles calculations. The results predict that magnetic anisotropy behavior with its easy magnetization axis stability keeps in-plane with altering stacking orders and biaxial strain from −6% to 6%. The valley polarization of 2H-VTe₂ is well preserved in the 2H-VTe₂/1T-FeCl₂ heterostructures, and the most stable stacking configuration with type-I band alignment exhibits a large valley polarization of 156.5 meV, which can realize a maximum valley polarization of 166.6 meV at the compression strain of −4%. The biaxial strain remarkably alters the band structure of heterostructures and achieves the transitions from type-I to type-II and III band alignments as well as from semiconductor to metallic. The modulation of layer distance shows a weak effect on valley polarization and only can convert the band alignment from type-I to type-II. The significant variations of band alignments enable 2H-VTe₂/1T-FeCl₂ heterostructure to become an attractive candidate for optoelectronic and photocatalytic materials and also give rise to the possibility of valleytronics and spintronics application.