We report tunneling measurements of the superconducting energy gaps in YBa2Cu3O7 and Bi2Sr2CaCu2O8 using break junctions. The differential conductance dl/dV at T = 4.2 K shows no leakage around zero bias, while the gap edge peaks in dl/dV are somewhat broadened compared to the simple BCS density of states. This strongly suggests an s-wave superconductivity with an anisotropic gap. From the best data, we obtain a result that the gap anisotropy in Bi2Sr2CaCu2O8 is larger than that in YBa2Cu3O7.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering