Local density of state oscillations in laterally heterostructured topological insulator-semiconductor systems

TL;DR

This paper investigates how local density of state oscillations near atomic edge defects on topological insulator surfaces are influenced by heterostructure interfaces, revealing decay behavior and dependence on interface details.

Contribution

It provides a theoretical analysis of LDOS oscillations in TI-semiconductor heterostructures, highlighting the decay envelope's insensitivity to edge defects and the effects of spin textures and Fermi surface size.

Findings

LDOS oscillations decay as x^{-3/2} near the Dirac point.

Amplitude variations depend on interface details and spin textures.

Oscillation period is determined by Fermi surface size.

Abstract

We study local density of state (LDOS) oscillations arising from the scattering of electrons at atomic edge defects in topological insulator (TI) surfaces. To create edge scattering on the surface of a TI, we assume that half of its surface is covered with a semiconductor. In addition to modifying the TI states in the covered half, the presence of the semiconductor leads to a localized edge potential at the vacuum-semiconductor boundary. We study the induced LDOS by imposing time-reversal (TR) invariance and current conservation across the boundary. Additionally, we explore how the scattering of TI junctions with dissimilar spin textures and anisotropic Fermi velocities affect the modulations of the LDOS away from the junction edge. In all cases, for energies close to the Dirac point, we find that the decay envelope of the LDOS oscillations is insensitive to the scattering at the atomic edge defect, with a decay power given by $x^{-3/2}$. Quantitative differences in the amplitude of these oscillations depend on the details of the interface and the spin textures, while the period of the oscillations is defined by the size of the Fermi surface.