Superconductivity suppression and bilayer decoupling in Pr-substituted YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-<i>δ</i></sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 42127115.
- Also identified by DOI 10.1073/pnas.2536919123 and PMC identifier 13187780.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The mechanism behind superconductivity suppression induced by Pr substitutions in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-<i>δ</i></sub> (YBCO) has been a mystery since its discovery: in spite of being isovalent to Y<sup>3+</sup> 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+[Formula: see text] 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 <i>f</i>-electron hybridization or additional <i>f</i>-state Fermi surface sheets. 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<sub>2</sub> bilayer decoupling and enhanced hopping along the CuO chain, implying indirect electron-release pathways beyond simple 4<i>f</i> 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.