Bismuth (Bi) films hold potential for spintronic devices and topological one-dimensional edge transport. Large-area high-quality (111) Bi ultrathin films are grown on InSb (111)B substrates. Strong film-substrate interactions epitaxially stabilize the (111) orientation and lead to inversion symmetry breaking. We resolve the longstanding controversy over the Z_2 topological assignment of bismuth and show that the surface states are topologically trivial. Our results demonstrate that interfacial bonds prevent the semimetal-to-semiconductor transition predicted for freestanding bismuth layers, highlighting the importance of controlled functionalization and surface passivation in two-dimensional materials.
@article{arxiv.2302.00803,
title = {Inversion Symmetry Breaking in Epitaxial Ultrathin Bi (111) Films},
author = {Hadass S. Inbar and Muhammad Zubair and Jason T. Dong and Aaron N Engel and Connor P. Dempsey and Yu Hao Chang and Shinichi Nishihaya and Shoaib Khalid and Alexei V. Fedorov and Anderson Janotti and Chris J. Palmstrøm},
journal= {arXiv preprint arXiv:2302.00803},
year = {2025}
}