Spin-orbit-stable type-II nodal line band crossing in n -doped monolayer MoX2 (X=S, Se,Te)

Abstract

1H-phase monolayer transition-metal dichalcogenides have spin-split electronic band structures near the K(K��) point due to strong spin-orbit coupling and intrinsic inversion symmetry breaking. In the case of the monolayer MoX2 (X=S, Se, Te), the spin-split conduction bands cross near the K(K��) point. We show that the band crossing occurs not only along the high-symmetry directions, but also along arbitrary directions due to a mirror reflection symmetry of the monolayer. As a result, n-doped monolayer MoX2 is a two-dimensional type-II nodal-line material. ? 2018 American Physical Society