Design Principles for High Temperature Superconductors with Hydrogen-based Alloy Backbone at Moderate Pressure

TL;DR

This paper proposes a rational design strategy for high-temperature superconductors using hydrogen-based alloy backbones, predicting new materials that could achieve superconductivity at significantly lower pressures than current options.

Contribution

It introduces a novel approach to designing low-pressure high-Tc superconductors by alloying elements to form stable ternary hydrides with high critical temperatures.

Findings

LaBeH8 predicted to be superconducting at 191 K and 50 GPa

Identification of a fluorite-type alloy backbone in AXH8 compounds

Potential to discover high-Tc superconductors near ambient pressure

Abstract

Hydrogen-based superconductors provide a route to the long-sought goal of room-temperature superconductivity, but the high pressures required to metallize these materials limit their immediate application. For example, carbonaceous sulfur hydride, the first room-temperature superconductor, can reach a critical temperature (Tc) of 288 K only at the extreme pressure of 267 GPa. The next recognized challenge is the realization of room-temperature superconductivity at significantly lower pressures. Here, we propose a strategy for the rational design of high-temperature superconductors at low pressures by alloying small-radius elements and hydrogen to form ternary hydride superconductors with alloy backbones. We identify a hitherto unknown fluorite-type backbone in compositions of the form AXH8, which exhibit high temperature superconductivity at moderate pressures. The Fm-3m phase of LaBeH8, with a fluorite-type H-Be alloy backbone, is predicted to be metastable and superconducting with a Tc ~ 191 K at 50 GPa; a substantially lower pressure than that required by the geometrically similar clathrate hydride LaH10 (170 GPa). Our approach paves the way for finding high-Tc ternary hydride superconductors at conditions close to ambient pressures.