Superconductivity in twisted bismuth bilayers

TL;DR

This study uses first-principles calculations to explore superconductivity in twisted bismuth bilayers, predicting a maximum T_c of about 1.8 K at a specific twist angle, significantly higher than the known value for crystalline bismuth.

Contribution

It introduces a theoretical prediction of enhanced superconductivity in twisted bismuth bilayers at specific angles, expanding understanding of twist-induced superconductivity.

Findings

Metallic character observed at various twist angles.

Predicted maximum T_c of approximately 1.8 K at 0.5° twist.

Superconducting T_c exceeds the experimental value for crystalline bismuth.

Abstract

First-principles calculations for two twisted bismuth bilayers, each with 120 atoms, were studied by means of the electronic density of states and vibrational density of states. Metallic character at the Fermi level was found for the non-rotated sample as well as for each sample rotated 0.5{\deg}, 1.0{\deg}, 1.5{\deg}, 2.0{\deg}, 2.5{\deg}, 3.0{\deg}, 4.0{\deg}, 5.0{\deg}, 6.0{\deg}, 7.0{\deg}, 8.0{\deg} and 10{\deg} with respect to the static bilayer. Assuming that the superconductivity is BCS-type and the invariance of the Cooper pairing potential, we predict a maximum superconducting temperature T_c ~ 1.8 K for a magic angle of 0.5{\deg} degrees between the two bilayers, increasing the superconducting transition temperature from the experimentally measured value of 0.53 mK for the Wyckoff structure of crystalline bismuth.