How pressure enhances the critical temperature of superconductivity in YBa${}_2$Cu${}_3$O${}_{6+y}$

Abstract

High-temperature superconducting cuprates respond to doping with a dome-like dependence of their critical temperature ($T_{\mathrm{c}}$). But the family specific maximum $T_{\mathrm{c}}$ can be surpassed by application of pressure, a compelling observation known for decades. We investigate the phenomenon with high-pressure anvil cell nuclear magnetic resonance (NMR) and measure the charge content at planar Cu and O, and with it the doping of the ubiquitous CuO${}_2$ plane with atomic scale resolution. We find that pressure increases the overall doping, as widely assumed, but when it enhances $T_{\mathrm{c}}$ above what can be achieved by doping, it leads to a hole redistribution favoring planar O. This is similar to the observation that the family-specific maximum $T_{\mathrm{c}}$ also increases if the hole content at planar O is raised at the expense of that at planar Cu. Thus, the pressure-induced enhancement of $T_{\mathrm{c}}$ points to the same mechanism.

10 pages, 5 figures

Cited by in corpus (1)

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