Superconductivity suppression and bilayer decoupling in Pr substituted YBa$_2$Cu$_3$O$_{7-\delta}$

Jinming Yang; Zheting Jin; Siqi Wang; Camilla Moir; Mingyu Xu; Brandon Gunn; Xian Du; Zhibo Kang; Keke Feng; Makoto Hashimoto; Donghui Lu; Jessica McChesney; Martin Sundermann; Hlynur Gretarsson; Shize Yang; Wei-Wei Xie; Alex Frano; Sohrab Ismail-Beigi; M. Brian Maple; Yu He

arXiv · 2510.15078

Superconductivity suppression and bilayer decoupling in Pr substituted YBa$_2$Cu$_3$O$_{7-\delta}$

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Abstract

The mechanism behind superconductivity suppression induced by Pr substitutions in YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) has been a mystery since its discovery: in spite of being isovalent to Y$^{3+}$ with a small magnetic moment, it is the only rare-earth element that has a dramatic impact on YBCO's superconducting properties. Using angle-resolved photoemission spectroscopy (ARPES) and DFT+$U$ calculations, we uncover how Pr substitution modifies the low-energy electronic structure of YBCO. Contrary to the prevailing Fehrenbacher-Rice (FR) and Liechtenstein-Mazin (LM) models, the low energy electronic structure contains no signature of any $f$-electron hybridization or new states. Yet, strong electron doping is observed primarily on the antibonding Fermi surface. Meanwhile, we reveal major electronic structure modifications to Cu-derived states with increasing Pr substitution: a pronounced CuO$_2$ bilayer decoupling and an enhanced CuO chain hopping, implying indirect electron-release pathways beyond simple 4$f$ state ionization. Our results challenge the long-standing FR/LM mechanism and establish Pr substituted YBCO as a potential platform for exploring correlation-driven phenomena in coupled 1D-2D systems.

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Jinming Yang, Zheting Jin, Siqi Wang, Camilla Moir, Mingyu Xu, Brandon Gunn, Xian Du, Zhibo Kang, Keke Feng, Makoto Hashimoto, Donghui Lu, Jessica McChesney, Martin Sundermann, Hlynur Gretarsson, Shize Yang, Wei-Wei Xie, Alex Frano, Sohrab Ismail-Beigi, M. Brian Maple, Yu He. 2025-10-16. Superconductivity suppression and bilayer decoupling in Pr substituted YBa$_2$Cu$_3$O$_{7-\delta}$. https://arxiv.org/abs/2510.15078

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