Strong coupling, fluctuations and the specific heat of YBa₂,Cu₃O_7-δ

Abstract

Specific-heat data on the high-temperature superconductor YBa₂Cu₃O_7-δ provide evidence for strong coupling. The data on ceramic and single-crystal samples also indicate that, when there is a fluctuation contribution to the specific-heat anomaly at T_c' the anomaly is reduced in height. These results are consistent with the idea that an oxygen deficiency reduces γ and enhances fluctuation effects.