Suppression of Conductance in a Topological Insulator Nanostep Junction

TL;DR

This paper studies quantum transport in a topological insulator nanostep junction, revealing a universal conductance suppression and a distinctive Fano factor behavior due to surface state scattering.

Contribution

It introduces a theoretical analysis of conductance suppression and Fano factor in nanostep junctions on topological insulators, highlighting universal and novel transport properties.

Findings

Conductance is suppressed by a factor of 1/3 compared to planar junctions.

Fano factor saturates at 1/5, indicating reduced noise.

Universal conductance suppression is linked to the nanostep geometry.

Abstract

We investigate quantum transport via surface states in a nanostep junction on the surface of a 3D topological insulator that involves two different side surfaces. We calculate the conductance across the junction within the scattering matrix formalism and find that as the bias voltage is increased, the conductance of the nanostep junction is suppressed by a universal factor of 1/3 compared to the conductance of a similar planar junction based on a single surface of a topological insulator. We also calculate and analyze the Fano factor of the nanostep junction and predict that the Fano factor saturates at 1/5, five times smaller than for a Poisson process.