Electronic phase transitions of bismuth under strain from relativistic self-consistent GW calculations

TL;DR

This paper uses advanced relativistic self-consistent GW calculations to accurately predict how small strains can induce topological phase transitions in bismuth, aligning theory with experimental feasibility.

Contribution

It introduces a relativistic QSGW method including spin-orbit coupling for better electronic structure predictions of Bi under strain.

Findings

Small strains (~0.3-0.4%) induce phase transitions in Bi.

Relativistic QSGW aligns well with experimental data.

Transitions are experimentally accessible.

Abstract

We present quasiparticle self-consistent GW (QSGW) calculations of semimetallic bulk Bi. We go beyond the conventional QSGW method by including the spin-orbit coupling throughout the self-consistency cycle. This approach improves the description of the electron and the hole pockets considerably with respect to standard density functional theory (DFT), leading to excellent agreement with experiment. We employ this relativistic QSGW approach to conduct a study of the semimetal-to-semiconductor and the trivial-to-topological transitions that Bi experiences under strain. DFT predicts that an unphysically large strain is needed for such transitions. We show, by means of the relativistic QSGW description of the electronic structure, that an in-plane tensile strain of only 0.3% and a compressive strain of 0.4% are sufficient to cause the semimetal-to-semiconductor and the trivial-to-topological phase transitions, respectively. Thus, the required strain moves into a regime that is likely to be realizable in experiment, which opens up the possibility to explore bulklike topological behavior of pure Bi.