A large anisotropy of superconducting energy gap in Bi2Sr2CaCu2O8 was directly observed by high-energy resolution angle-resolved photoemission spectroscopy with a high-quality twin-free single crystal. The superconducting gap (Δ) observed in the ΓM direction is 17-19 meV while that in the ΓX (or ΓY) direction is 0-2 meV, suggesting the dx2-y2 superconducting order parameter.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering