Search for thermodynamically stable ambient-pressure superconducting hydrides in GNoME database

TL;DR

This study systematically searches for thermodynamically stable ambient-pressure hydrides with superconductivity, identifying 25 stable cubic hydrides with critical temperatures up to 17 K using machine learning and ab initio methods.

Contribution

It introduces a multi-stage approach combining machine learning and ab initio calculations to identify stable hydrides with potential superconductivity at room pressure.

Findings

Identified 25 stable cubic hydrides with $T_c$ above 4.2 K.

Maximum $T_c$ found is 17 K.

Stable hydrides at ambient pressure are experimentally accessible.

Abstract

Hydrides are considered to be one of the most promising families of compounds for achieving high temperature superconductivity. However, there are very few experimental reports of ambient-pressure hydride superconductivity, and the superconducting critical temperatures ($T_{\rm c}$) are typically less than 10 K. At the same time several hydrides have been predicted to exhibit superconductivity around 100 K at ambient pressure but in thermodynamically unfavorable phases. In this work we aim at assessing the superconducting properties of thermodynamically stable hydride superconductors at room pressure by investigating the GNoME material database, which has been recently released and includes thousands of hydrides thermodynamically stable at 0K. To scan this large material space we have adopted a multi stage approach which combines machine learning for a fast initial evaluation and cutting edge ab initio methods to obtain a reliable estimation of ($T_{\rm c}$). Ultimately we have identified 25 cubic hydrides with ($T_{\rm c}$) above 4.2~K and reach a maximum ($T_{\rm c}$) of 17 K. While these critical temperatures are modest in comparison to some recent predictions, the systems where they are found, being stable, are likely to be experimentally accessible and of potential technological relevance.