An Effective Descriptor for Predicting and Designing High-Temperature Ambient-Pressure Superconductors

Abstract

Searching for ambient-pressure conventional superconductors with critical temperatures (TC) higher than 40 K is a key challenge in the field of high-temperature superconductivity, mainly due to lack of efficient and effective models to estimate TC of potential systems. In this work, we propose a simplified model to estimate the dimensionless electron-phonon coupling (EPC) strength {\lambda} by separately treating the EPC matrix elements which evaluate the pairing strength and the phonon-assisted nesting function P({\omega}) which evaluates the matching of electron bands and phonon spectra for forming potential electron pairs via phonons. Our model illuminates the critical role of P({\omega}) and its spectral integral P in determining {\lambda}, i.e., high P is a necessary condition leading to large {\lambda} and thus high TC, which is further demonstrated by showing that the reported high-TC traditional superconductors in literatures all have high P. As an easily quantifiable parameter, P({\omega}) and P provide an efficient and effective descriptor for accelerating the discovery and rational design of high-TC superconductors. By applying the model to screen over the Computational 2D Materials Database (C2DB), we successfully identify several high-TC superconducting systems as confirmed by accurate first-principles calculations. Our model opens new avenues for exploring high-TC systems.