Effects of strain and stacking patterns on the electronic structure, valley polarization and magnetocrystalline anisotropy of layered VTe2

Abstract

Effects of strain and stacking patterns on the electronic structure, valley polarization and magnetocrystalline anisotropy (MA) of layered VTe2 are studied by first principles calculations. The results show that the VTe2 monolayer possesses a large spontaneous valley polarization of 156.5 meV and in-plane ferromagnetic ground state with Curie temperature of 377 K. The large valley polarization mainly originates from the spontaneous magnetic exchange field rather than the SOC effect based on the effective Hamiltonian k·p model. The orbital-resolved magnetocrystalline anisotropy energy (MAE) of V atoms shows that the observed in-plane MAE mainly originates from the contribution of dxy and dx2-y2 orbitals of V atoms. With the increase of strain from −6% to 6%, the VTe2 monolayer still maintains in-plane MA, but its MAE and valley polarization firstly increases and then gradually decreases, which are strongly related to the magnetic moment of V atoms. The stacking patterns can remarkably influence the valley polarization of layered VTe2. The AB stacking pattern retains the space inversion symmetry, resulting that the valley polarization remarkably decreases or even disappears. On the contrary, the AA stacking pattern keeps a larger valley polarization due to break the space inversion symmetry. The layered VTe2 possesses intrinsic ferromagnetism, tunable MA and valley polarization, which supports the possibility of applications in valleytronics, optoelectronics and other fields.