Ab initio prediction of nontrivial topological band and superconductivity in stable metallic Si allotropes at ambient pressure

Abstract

Silicon is a semiconductor and widely used as the key element for modern electronic devices. Various metallic superconducting phases have been reported, but most retain their crystal structure at high pressures. Thus, it remains a challenge to search for potential superconducting Si allotropes. In this article, the authors propose novel metallic Si allotropes that meet the conditions for dynamic, mechanical, and thermal stability at ambient pressure through machine learning and first-principles electronic structure calculations. The new allotropes are superconductors and even exhibit a nontrivial band topology, providing a promising platform for realizing a topological superconducting state in all-Si systems.