# Nano-mosaic of Topological Dirac States on the Surface of Pb5Bi24Se41 Observed by Nano-ARPES

## TL;DR

This study uses nano-ARPES to visualize a mosaic of topological Dirac states on the surface of Pb5Bi24Se41, revealing how local topological band structures vary with nano-island thickness, advancing understanding of topological heterostructures.

## Contribution

First application of nano-ARPES to directly observe nanoscale topological Dirac states on a complex heterostructure surface.

## Key findings

- Visualization of topological Dirac states at nanometer scale
- Identification of band structure variation with nano-island thickness
- Nano-ARPES as a powerful tool for topological heterostructure analysis

## Abstract

We have performed scanning angle-resolved photoemission spectroscopy with a nanometer-sized beam spot (nano-ARPES) on the cleaved surface of Pb5Bi24Se41, which is a member of the (PbSe)5(Bi2Se3)3m homologous series (PSBS) with m = 4 consisting of alternate stacking of the topologically-trivial insulator PbSe bilayer and four quintuple layers (QLs) of the topological insulator Bi2Se3. This allows us to visualize a mosaic of topological Dirac states at a nanometer scale coming from the variable thickness of the Bi2Se3 nano-islands (1-3 QLs) that remain on top of the PbSe layer after cleaving the PSBS crystal, because the local band structure of topological origin changes drastically with the thickness of the Bi2Se3 nano-islands. A comparison of the local band structure with that in ultrathin Bi2Se3 films on Si(111) gives us further insights into the nature of the observed topological states. This result demonstrates that nano-ARPES is a very useful tool for characterizing topological heterostructures.