Here we report a structural phase transition and its possible competition with superconductivity in the suboxide La5Pb3O. Upon cooling through Tt = 225 K, La5Pb3O transforms from a high-temperature I4/mcm to a low-temperature P4/ncc structure in which La - Pb dimerization along the c-axis occurs. This transition is accompanied by anomalies in the temperature dependence of electrical resistivity and specific heat. High-pressure electrical transport measurements reveal that hydrostatic pressure suppresses the structural transition and possibly induces superconductivity with a maximum superconducting temperature of 10 K. Density functional theory calculations show minimal changes in the electronic density of states and no gap opening at EF across Tt, suggesting that the transition is driven by bonding effects rather than Fermi surface instability. These findings establish La5Pb3O as a promising platform for exploring the interplay between weak structural transitions and superconductivity.
@article{arxiv.2508.10080,
title = {Structural transition and possible pressure-induced superconductivity in a suboxide La$_5$Pb$_3$O},
author = {Jiaqiang Yan and David Singh and Bayram Saparov and Huibo Cao and Yejun Feng and Jinguang Cheng and Yoshia Uwatoko and David Mandrus},
journal= {arXiv preprint arXiv:2508.10080},
year = {2025}
}