Anomalous conductance quantization of a one-dimensional channel in monolayer WSe2

Among quantum devices based on 2D materials, gate-defined quantum confined 1D channels are much less explored, especially in the high mobility regime where many body interactions play an important role. We present results of measurements and theory of conductance quantization in a gate-defined one dimensional channel in a single layer of transition metal dichalcogenide material WSe2. In the quasi-ballistic regime of our high mobility sample, we report conductance quantization steps in units of e2/h for a wide range of carrier concentrations. Magnetic field measurements show that as the field is raised higher conductance plateaus move to accurate quantized values and then shift to lower conductance values while the e2/h plateau remains locked. Based on microscopic atomistic tight-binding theory, we show that in this material, valley and spin degeneracies result in 2 e2/h conductance steps for non-interacting holes, suggesting that symmetry breaking mechanisms such as valley polarization dominate the transport properties of such quantum structures.