Subband Structure and Ballistic Conductance of a Molybdenum Disulfide Nanoribbon in Topological 1T’ Phase: A k·p Study

Abstract

We evaluate the subband structure in a narrow nanoribbon of 1T’ molybdenum disulfide by employing an effective $\mathrm{k}\cdot \mathrm{p}$ Hamiltonian. Highly conductive topologically protected edge states whose energies lie within the bulk band gap are investigated. Due to the interaction of the edge modes located at the opposite edges, a small gap in their linear spectrum opens in a narrow nanoribbon. This gap is shown to sharply increase with the perpendicular out-of-plane electric field, in contrast to the behavior in a wide nanoribbon. The gaps between the electron and hole bulk subbands also increase with the electric field. The increase of the gaps between the subbands leads to a rapid decrease of the ballistic nanoribbon conductance and current with the gate voltage, which can be used for designing molybdenum disulfide nanoribbon-based current switches.