How pressure enhances the critical temperature of superconductivity in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6+<i>y</i></sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36608293.
- Also identified by DOI 10.1073/pnas.2215458120 and PMC identifier 9926205.
- 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
High-temperature superconducting cuprates respond to doping with a dome-like dependence of their critical temperature (<i>T</i><sub>c</sub>). But the family-specific maximum <i>T</i><sub>c</sub> can be surpassed by application of pressure, a compelling observation known for decades. We investigate the phenomenon with high-pressure anvil cell NMR and measure the charge content at planar Cu and O, and with it the doping of the ubiquitous CuO<sub>2</sub> plane with atomic-scale resolution. We find that pressure increases the overall hole doping, as widely assumed, but when it enhances <i>T</i><sub>c</sub> above what can be achieved by doping, pressure leads to a hole redistribution favoring planar O. This is similar to the observation that the family-specific maximum <i>T</i><sub>c</sub> is higher for materials where the hole content at planar O is higher at the expense of that at planar Cu. The latter reflects dependence of the maximum <i>T</i><sub>c</sub> on the Cu-O bond covalence and the charge-transfer gap. The results presented here indicate that the pressure-induced enhancement of the maximum <i>T</i><sub>c</sub> points to the same mechanism.