Robust non-integer conductance in disordered 2D Dirac semimetals

We study the conductanceGof 2D Dirac semimetal nanowires at the presence of disorder. For an even nanowire lengthLdetermined by the number of unit cells, we find non-integer values forGthat are independent ofLand persist with weak disorder, indicated by the vanishing fluctuations ofG. The effect is created by a combination of the scattering effects at the contacts (interface) between the leads and the nanowire, an energy gap present in the nanowire for evenLand the topological properties of the 2D Dirac semimetals. Unlike conventional materials the reducedGdue to the scattering at the interface, is stabilized at non-integer values inside the nanowire, leading to a topological phase for weak disorder. For strong disorder the system leaves the topological phase and the fluctuations ofGare increased as the system undergoes a transition/crossover toward the Anderson localized (insulating) phase, via a non-standard disordered phase. We study the scaling and the statistics ofGat these phases. In addition we have found that the effect of robust non-integerGdisappears for oddL, which results in integerG, determined by the number of open channels in the nanowire, due to resonant scattering.