Weyl semimetal states in transition metal monochalcogenide superlattices AX/BX (A, B = Cr, Mo, W, A ≠ B; X = Se, Te)

Based on first-principles calculations and the Wannier-function-based tight-binding method, we investigate the topological electronic properties of designed noncentrosymmetric transition metal monochalcogenide superlattices AX/BX (A, B = Cr, Mo, W, A ≠ B; X = Se, Te). Here, we mainly consider time-reversal symmetry (TRS) MoTe/WTe and MoSe/WSe and TRS broken CrTe/WTe and CrTe/MoTe, which are the Weyl and magnetic Weyl semimetals, respectively. The considered systems are nodal line semimetals with nodal lines on three mirror planes of the Brillouin zone of hexagonal lattice in the absence of spin–orbit coupling (SOC). When considering the SOC, each nodal line opens a gap except for some pairs of Weyl points (WPs) on the k z ≠ 0 planes and the number of WPs is material-dependent. We identify the termination-dependent Fermi arc connection patterns on the (001) and (00 1 ˉ ) surfaces for four Weyl semimetal superlattices AX/BX. These results provide a theoretical basis to realize the possible applications of these superlattice materials in future topological electronic devices.