Metal hydrides achieve high-Tc superconductivity at low pressure by mimicking high-pressure H3S chemical bonding

TL;DR

This paper introduces a novel mechanism mimicking high-pressure H3S bonding in metal hydrides, enabling high-Tc superconductivity at low pressures through structural stabilization and enhanced electron-phonon interactions.

Contribution

It demonstrates a new approach using covalent bonding frameworks to stabilize hydrides at low pressures while maintaining high superconducting transition temperatures.

Findings

Li3CuH4 is stable at 20 GPa with Tc of 39.25 K at 12 GPa

Covalent Cu-H interactions mimic H3S bonding, enhancing electron density and phonon softening

High-throughput studies reveal principles applicable to other transition metal hydrides

Abstract

Compressed hydrides are promising candidates for high-temperature superconductivity, yet achieving simultaneous structural stability and high-Tc at low pressures remains challenging. Here, we introduce a new mechanism for accomplishing this goal by mimicking the bonding characteristics of high-pressure H3S within metal hydrides. Using Li3CuH4 as an example, its Cu-H covalent interaction effectively mimics the core function of the S-H bonding in H3S. This interaction not only induces a high hydrogen-derived electronic density of states at the Fermi level, but also softens the hydrogen phonon modes, thereby significantly enhancing the electron-phonon coupling. Furthermore, embedding the strongly ionic Li3H lattice into the covalent Cu-H framework stabilizes the structure at significantly low pressures via a chemical-template effect, while maintaining high-Tc. Li3CuH4 exhibits excellent thermodynamic stability at 20 GPa, with a Tc of 39.25 K at 12 GPa. Further comprehensive high-throughput studies on Li3MH4 (M = transition metal) compounds uncover general principles applicable to a broader range of compounds. This work establishes a new paradigm for the simultaneous optimization of the stability and high-temperature superconductivity of metal hydrides through complementary sublattice interactions, thus advancing the search for practical and viable superconducting materials.