Plateaus of quantized conductance with high steps in topological nodal-line semimetals

Abstract

Topological nodal-line semimetals (TNLSMs) are a new state of quantum matter. It has one-dimensional energy band intersections where the conduction band and valence band cross to form one or more nodal rings. Here, based on the Landauer-B\"uttiker formula combined with the nonequilibrium Green's function method, we investigate the electron transport through TNLSM nanowires under a perpendicular magnetic field. We theoretically calculate the conductance of TNLSM nanowires and find that it is essentially different from other topological and trivial materials. The conductance of TNLSM nanowires presents the high plateaus with high steps in multiples of ${e}^{2}/h$. The height of the steps is determined by the size of the nanowire and for a TNLSM nanowire with the size of several tens of nanometers, its conductance plateaus can reach hundreds of ${e}^{2}/h$ with the step height being tens of ${e}^{2}/h$. The unique phenomenon of the high-stepped conductance plateaus originates from the peculiar energy spectrum of the TNLSMs, that is, there are a lot of subbands having the same energy minimum value. Furthermore, the high conductance plateaus and the high steps can well remain in the existence of magnetic fields, the moderate disorder, and the PT-symmetry-breaking mass term. This unique conductance characteristic can serve as a reliable signature of TNLSMs in experimental detections.