TThe isotope effect is a powerful probe of electron-phonon interactions in solid-state systems, offering key insights into how atomic mass influences emergent quantum states. Here, the impact of oxygen isotope substitution (16O→18O) on charge- and spin-density wave (CDW and SDW) transitions in the double-layer Ruddlesden-Popper nickelate La3Ni2O7 is investigated. A clear isotope effect is observed in the CDW transition: the transition temperature (TCDW) increases upon 18O substitution. In contrast, the SDW transition temperature remains unaffected within experimental uncertainty. These findings point to a strong involvement of lattice vibrations in the formation of charge order, while spin order appears to be predominantly of electronic origin. The results suggest that electron-phonon coupling, manifested through the CDW response to isotope substitution, may be relevant to the superconducting pairing mechanism in Ruddlesden-Popper nickelates.
@article{arxiv.2504.08290,
title = {Oxygen-isotope effect on density wave transitions in La$_3$Ni$_2$O$_{7}$},
author = {Rustem Khasanov and Vahid Sazgari and Igor Plokhikh and Lifen Shi and KeYuan Ma and Marisa Medarde and Ekaterina Pomjakushina and Tomasz Klimczuk and Thomas J. Hicken and Hubertus Luetkens and Christof W. Schneieder and Zurab Guguchia and Sergey Medvedev and Dariusz J. Gawryluk},
journal= {arXiv preprint arXiv:2504.08290},
year = {2026}
}