Phonon-mediated superconductivity in two-dimensional hydrogenated phosphorus carbide: HPC$_{3}$

TL;DR

This study predicts that hydrogenated monolayer phosphorus carbide (HPC3) exhibits high-temperature superconductivity at 31 K, which can be enhanced to over 57 K with strain, highlighting a promising 2D superconductor at ambient pressure.

Contribution

First-principles calculations reveal hydrogenation induces superconductivity in 2D phosphorus carbide, with strain further boosting the critical temperature beyond the McMillan limit.

Findings

HPC3 transitions from semiconductor to metal after hydrogenation.

Electron-phonon coupling constant is 0.95, mainly from C-$ ext{pi}$ electrons.

Critical temperature can reach 57.3 K under 3% biaxial strain.

Abstract

In the recent years, three-dimensional (3D) high-temperature superconductors at ultrahigh pressure have been reported, typical examples are the polyhydrides H$_{3}$S, LaH$_{10}$, and YH$_{9}$, etc. To find high-temperature superconductors in two-dimensional (2D) at atmosphere pressure is another research hotspot. Here, we investigated the possible superconductivity in a hydrogenated monolayer phosphorus carbide based on first-principles calculations. The results reveal that monolayer PC$_{3}$ transforms from a semiconductor to a metal after hydrogenation. Interestingly, the C-$\pi$-bonding band contributes most to the states at the Fermi level. Based on the electron-phonon coupling mechanism, it is found that the electron-phonon coupling constant of HPC$_{3}$ is 0.95, which mainly origins from the coupling of C-$\pi$ electrons with the in-plane vibration modes of C and H. The calculated critical temperature $T_{c}$ is 31.0 K, which is higher than most of the 2D superconductors. By further applying biaxial tensile strain of 3$\%$, the $T_{c}$ can be boosted to 57.3 K, exceeding the McMillan limit. Thus, hydrogenation and strain are effective ways for increasing the superconducting $T_{c}$ of 2D materials.