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

We evaluate the subband structure in a narrow nanoribbon of 1T' molybdenum disulfide by employing an effective k·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.