The topology of pure Bi is controversial because of its very small (∼10 meV) band gap. Here we perform high-resolution angle-resolved photoelectron spectroscopy measurements systematically on 14−202 bilayers Bi films. Using high-quality films, we succeed in observing quantized bulk bands with energy separations down to ∼10 meV. Detailed analyses on the phase shift of the confined wave functions precisely determine the surface and bulk electronic structures, which unambiguously show nontrivial topology. The present results not only prove the fundamental property of Bi but also introduce a capability of the quantum-confinement approach.
@article{arxiv.1605.03531,
title = {Proving Nontrivial Topology of Pure Bismuth by Quantum Confinement},
author = {S. Ito and B. Feng and M. Arita and A. Takayama and R. -Y. Liu and T. Someya and W. -C. Chen and T. Iimori and H. Namatame and M. Taniguchi and C. -M. Cheng and S. -J. Tang and F. Komori and K. Kobayashi and T. -C. Chiang and I. Matsuda},
journal= {arXiv preprint arXiv:1605.03531},
year = {2016}
}