Proximity-Coupled CuO ₂ Planes in High- <i>T</i> _c Superconductors: Evidence from Pressure Experiments up to 34 GPa on Y ₂ Ba ₄ Cu ₇ O _15.32

Abstract

The Tc of superconducting Y2Ba4Cu7O15.32 is measured up to a pressure of 33.7 GPa. After an initial increase from 95 K to 101.7 K a decrease down to 26.6 K is found, with a clear kink at 22 GPa. We demonstrate that Y2Ba4Cu7O15.32 behaves as a multilayer of YBa2Cu3O7 and YBa2Cu4O8 building blocks coupled via the proximity effect. These data are not consistent with the idea that the coupling of two adjacent CuO2 planes is necessary for superconductivity.