Evidence of Molecular Hydrogen in the N-doped LuH3 System: a Possible Path to Superconductivity?

TL;DR

This study uses machine learning to identify hydrogen molecules stabilized by nitrogen in N-doped LuH3, suggesting a possible route to ambient-pressure superconductivity through molecular hydrogen phases.

Contribution

It introduces a novel computational approach to identify stable molecular hydrogen in hydrides, linking it to potential ambient-pressure superconductivity.

Findings

Hydrogen molecules are stabilized at ambient pressure by nitrogen impurities.

Molecular hydrogen phases may be key to achieving ambient-pressure superconductivity.

The approach opens new avenues for studying disordered hydride phases.

Abstract

The discovery of ambient superconductivity would mark an epochal breakthrough long-awaited for over a century, potentially ushering in unprecedented scientific and technological advancements. The recent findings on high-temperature superconducting phases in various hydrides under high pressure have ignited optimism, suggesting that the realization of near-ambient superconductivity might be on the horizon. However, the preparation of hydride samples tends to promote the emergence of various metastable phases, marked by a low level of experimental reproducibility. Identifying these phases through theoretical and computational methods entails formidable challenges, often resulting in controversial outcomes. In this paper, we consider N-doped LuH3 as a prototypical complex hydride: By means of machine-learning-accelerated force-field molecular dynamics, we have identified the formation of H2 molecules stabilized at ambient pressure by nitrogen impurities. Importantly, we demonstrate that this molecular phase plays a pivotal role in the emergence of a dynamically stable, low-temperature, experimental-ambient-pressure superconductivity. The potential to stabilize hydrogen in molecular form through chemical doping opens up a novel avenue for investigating disordered phases in hydrides and their transport properties under near-ambient conditions.