First principles investigation of the Co(0001)/MoS_2 and Ni(lll)/WSe_2 interfaces for spin injection in a transition metal dichalcogenide monolayer

摘要

The hexagonal close-packed (hcp) Co(0001)/MoS_2 and face-centered cubic (fcc) Ni(111)/WSe_2 interface atomic, magnetic and electronic structures are investigated using first-principles methods based on the density functional theory. We show that the MoS_2 and WSe_2 single layers are covalently bond to the Co(0001) and Ni(111) metal surfaces. We describe the consequences of this bonding on the spin magnetic moments and on the electron states at the vicinity of these interfaces, where MoS_2 and WSe_2 become metallic due to hybridization between Co (or Ni) and S (or Se) atomic orbitals. A finite spin-polarization at the Fermi level is calculated in the MoS_2 and WSe_2 layers at these two interfaces. We also give and estimation of the Schottky barrier height that may appear at the border between the metallic and semiconducting phases of MoS_2 (or WSe_2) near the edge of a Co/MoS_2 or Ni/WSe_2 metallic contact.