Correlation between plasma frequency and superconducting transition temperature in YBa2Cu3Oy

TLDR: In this article, the authors measured the reflectivity spectra of YBa 2 Cu 3 O y for various oxygen content and found that the plasma edge shifts towards lower energy with decreasing oxygen content, hence with decreasing T c.

Abstract: The plasma reflectivity spectra of YBa 2 Cu 3 O y were measured for various oxygen content y . It was found that the plasma edge shifts towards lower energy with decreasing oxygen content y , hence with decreasing T c . This result is discussed, together with the result on the Hall coefficient, based on the Mott-Hubbard and the Fermi liquid picture. It turns out that the latter is appropriate to explain the plasmon behavior in the oxide superconductors. Comparing the plasma frequencies ω p of other oxide superconductors, we find the linear relation between ω 2 p and T c , which cannot be explained by the BCS-theory.