Strain-controlled electronic and magnetic properties of tVS2/hVS2 van der Waals heterostructures

The structural, electronic and magnetic properties of the T-phase and H-phase of the VS2 monolayer and their heterobilayers are studied by means of first-principles calculations. We find that the two phases of the VS2 monolayer are both ferromagnetic (FM) semiconductors and that these two monolayers form a typical van der Waals (vdW) heterostructure with a weak interlayer interaction. By comparing the energy of different magnetic configurations, the FM state of the tVS(2)/hVS(2) heterostructure is found to be in the ground state under normal conditions or biaxial strains. Under compressive strains, the anti-FM (AFM) and FM states degenerate. Based on the band structure obtained and the work function, it is found that the T-phase and H-phase are capable of forming an efficient p-n heterostructure. Due to spontaneous charge transfer at the interface, a gapless semiconductor is formed in our HSE06 calculations. We also find that the twist angle between the monolayers has a negligible impact on the band structure of the heterostructure in its spin-down channel. Moreover, the tVS(2)/hVS(2) heterostructure is found to switch from a gapless semiconductor to a metal or a half-metal under some given biaxial or uniaxial strains. Therefore, the heterostructure could be a half-metallic property with strains, realizing 100% polarization at the Fermi level. Our study provides the possibility of realizing 100% spin-polarization at the Fermi level in these FM vdW heterostructures, which is significant for further spin transport exploration.

Automated summary

The T-phase and H-phase of the VS2 monolayer are both ferromagnetic semiconductors, forming a weakly interacting van der Waals heterostructure. The ferromagnetic state of the tVS(2)/hVS(2) heterostructure is found to be the ground state under normal conditions or biaxial strains, and can transition to a metal or half-metal under certain strains. This heterostructure has the potential to achieve 100% spin polarization at the Fermi level, which is significant for future spin transport exploration.