Competition between superconductivity and molecularization in the quantum nuclear behavior of lanthanum hydride

S. van de Bund, G. J. Ackland*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Lanthanum hydride is the superconductor with the highest known critical temperature. It is believed that the superconductivity is of standard BCS type, with electrons forming Cooper pairs and opening the superconducting band gap. Here, we show that the BCS electron pairing is in competition with an alternative pairing: covalent bonding. We show that the covalent pairing is favored at lower pressures, and the superconducting cubic phase becomes unstable as pressure is reduced. Previous calculations based on static relaxation neglect three factors, all of which are important in stabilizing the cubic phase. Finite temperature plays a role, and two quantum effects are also important - the nuclear wave function contributes to destabilizing the H2 molecules, and the zero-point pressure means that calculated pressures are significantly overestimated by standard methods. We demonstrate these phenomena using Born-Oppenheimer and path-integral molecular dynamics: These give the same qualitative picture, with nuclear quantum effects increasing the transition pressure significantly. This competition between molecularization and superconducting gap formation is the fundamental reason why hydride superconductors have so far been found only at high pressure.

Original languageEnglish
Article number184102
Pages (from-to)1-6
Number of pages6
JournalPhysical Review B
Issue number18
Publication statusPublished - 3 Nov 2023

Keywords / Materials (for Non-textual outputs)



Dive into the research topics of 'Competition between superconductivity and molecularization in the quantum nuclear behavior of lanthanum hydride'. Together they form a unique fingerprint.

Cite this