# Conductance of gated junctions as a probe of topological interface states

## TL;DR

This paper demonstrates that conductance measurements of gated junctions on topological insulators reveal key properties of topological interface states, including quasiparticle velocities and symmetry, providing a practical probe for interface characteristics.

## Contribution

It introduces a method to determine interface state properties via conductance oscillations and decay in gated junctions on topological insulators, independent of boundary conditions.

## Key findings

- Conductance oscillations depend on gate voltage.
- Quasi-linear decay reveals quasiparticle velocities.
- Results are insensitive to boundary conditions.

## Abstract

Energy dispersion and spin orientation of the protected states at interfaces between topological insulators (TIs) and non-topological materials depend on the charge redistribution, strain, and atomic displacement at the interface. Knowledge of these properties is essential for applications of topological compounds, but direct access to them in the interface geometry is difficult. We show that conductance of a gated double junction at the surface of a topological insulator exhibits oscillations and a quasi-linear decay as a function of gate voltage in different regimes. These give the values for the quasiparticle velocities along and normal to the junction in the interface region, and determine the symmetry of the topological interface states. The results are insensitive to the boundary conditions at the junction.