Strain-triggered high-temperature superconducting transition in two-dimensional carbon allotrope

TL;DR

This study demonstrates that applying biaxial tensile strain to a 2D carbon allotrope, THO-graphene, can induce superconductivity with a transition temperature up to 45 K, highlighting strain as a tool for controlling superconductivity in 2D materials.

Contribution

The paper reveals that purely strain-induced superconductivity can be achieved in a 2D carbon allotrope, setting a new record for transition temperature among 2D elemental superconductors.

Findings

Superconductivity in THO-graphene is induced solely by biaxial tensile strain.

The highest T_c achieved is 45 K under strain.

Strain enhances electron-phonon coupling enough to enable superconductivity.

Abstract

Driving non-superconducting materials into a superconducting state through specific modulation is a key focus in the field of superconductivity. Pressure is a powerful method that can switch a three-dimensional (3D) material between non-superconducting and superconducting states. In the two-dimensional (2D) case, strain engineering plays a similar role to pressure. However, purely strain-induced superconductivity in 2D systems remains exceedingly scarce. Using first-principles calculations, we demonstrate that a superconducting transition can be induced solely by applying biaxial tensile strain in a 2D carbon allotrope, THO-graphene, which is composed of triangles, hexagons, and octagons. Free-standing THO-graphene is non-superconducting. Surprisingly, the electron-phonon coupling in strained THO-graphene is enhanced strong enough to pair electrons and realize superconductivity, with the highest superconducting transition temperature reaching 45 K. This work not only provides a notable example of controlling metal-superconductor transition in 2D system just via strain, but also sets a new record of superconducting transition temperature for 2D elemental superconductors.