Many-body quantum muon effects and quadrupolar coupling in solids

Gomilšek, Matjaž; Pratt, Francis L.; Cottrell, Stephen P.; Clark, Stewart J.; Lancaster, Tom

Abstract

Strong quantum zero-point motion (ZPM) of light nuclei and other particles is a crucial aspect of many state-of-the-art quantum materials. However, it has only recently begun to be explored from an ab initio perspective, through several competing approximations. Here we develop a unified description of muon and light nucleus ZPM and establish the regimes of anharmonicity and positional quantum entanglement where different approximation schemes apply. Via density functional theory and path-integral molecular dynamics simulations we demonstrate that in solid nitrogen, α–N2, muon ZPM is both strongly anharmonic and many-body in character, with the muon forming an extended electric-dipole polaron around a central, quantum-entangled [N2–μ–N2]+ complex. By combining this quantitative description of quantum muon ZPM with precision muon quadrupolar level-crossing resonance experiments, we independently determine the static 14N nuclear quadrupolar coupling constant of pristine α–N2 to be –5.36(2) MHz, a significant improvement in accuracy over the previously-accepted value of –5.39(5) MHz, and a validation of our unified description of light-particle ZPM.

Citation

Gomilšek, M., Pratt, F. L., Cottrell, S. P., Clark, S. J., & Lancaster, T. (2023). Many-body quantum muon effects and quadrupolar coupling in solids. Communications Physics, 6(1), https://doi.org/10.1038/s42005-023-01260-7

• Journal Article Type: Article
• Acceptance Date: Jun 2, 2023
• Online Publication Date: Jun 16, 2023
• Publication Date: 2023
• Deposit Date: Jun 19, 2023
• Publicly Available Date: Aug 16, 2023
• Journal: Communications Physics.
• Electronic ISSN: 2399-3650
• Publisher: Nature Research
• Volume: 6
• Issue: 1
• DOI: https://doi.org/10.1038/s42005-023-01260-7
• Public URL: https://durham-repository.worktribe.com/output/1170024