Superconductivity at oxide interfaces has intrigued researchers for decades, yet the underlying pairing mechanism remains elusive. Here we demonstrate that proximity to a ferroelectric quantum critical point dramatically enhances interfacial superconductivity in KTaO3. By precisely tuning KTaO3 to its quantum critical composition through 0.8% niobium doping, we achieve a near-doubling of the superconducting transition temperature, reaching 2.9 K. Remarkably, a dome-shaped carrier density dependence emerges exclusively at the quantum critical point, contrasting sharply with the linear scaling observed in undoped interfaces. Our findings establish ferroelectric quantum criticality as a powerful mechanism for enhancing superconductivity and provide compelling evidence for soft-phonon-mediated pairing in these systems.
@article{arxiv.2511.12904,
title = {Enhanced Superconductivity at Quantum-Critical KTaO3 Interfaces},
author = {Jieun Kim and Muqing Yu and Ahmed Omran and Jiangfeng Yang and Ranjani Ramachandran and William O. Nachlas and Patrick Irvin and Jeremy Levy and Chang-Beom Eom},
journal= {arXiv preprint arXiv:2511.12904},
year = {2025}
}