Topologically Nontrivial Bismuth(111) Thin Films Grown on Bi2Te3

TL;DR

This study uses ARPES to reveal that Bi(111) thin films grown on Bi2Te3 are topologically nontrivial, showing unique surface states connecting bulk bands, differing from bulk bismuth.

Contribution

It provides experimental evidence that Bi(111) thin films on Bi2Te3 can be topologically nontrivial, highlighting new surface states and their connection to bulk bands.

Findings

Discovery of a new surface band near the M point

Odd number of Fermi crossings indicating nontrivial topology

Surface states connect bulk valence and conduction bands

Abstract

Using high-resolution angle-resolved photoemission spectroscopy, the electronic structure near the Fermi level and the topological property of the Bi(111) films grown on the Bi$_2$Te$_3$(111) substrate were studied. Very different from the bulk Bi, we found another surface band near the $\bar{M}$ point besides the two well-known surface bands on the Bi(111) surface. With this new surface band, the bulk valence band and the bulk conduction band of Bi can be connected by the surface states. Our band mapping revealed odd number of Fermi crossings of the surface bands, which provided a direct experimental signature that Bi(111) thin films of a certain thickness on the Bi$_2$Te$_3$(111) substrate can be topologically nontrivial in three dimension.