We performed de Haas-van Alphen (dHvA) oscillation measurements and band-structure calculations for YNi2B2C. Our improved band structure successfully explained the origins of the large dHvA frequencies β and ζ, which were inexplicable in previous works. By comparing experimental effective masses with band masses, we determined the electron-phonon coupling for each orbit. The results showed a clear Fermi-surface-sheet dependence of the electron-phonon coupling strength, especially highlighting that the coupling for the band-28 sheet is very weak, almost absent for the orbit with B∥c. This finding is consistent with previous observations of dHvA oscillations from this orbit in the mixed state down to very low fields. Amidst growing interest in high-temperature superconductivity driven by electron-phonon coupling in hydrides under high pressure, this study provides foundational data pivotal to precisely understanding electron-phonon coupling.
@article{arxiv.2601.01700,
title = {Fermi-surface-sheet dependent electron-phonon coupling in a borocarbide superconductor YNi$_2$B$_2$C},
author = {Taichi Terashima and Hiroyuki Takeya and Hisatomo Harima},
journal= {arXiv preprint arXiv:2601.01700},
year = {2026}
}