The authors present ARPES measurements on the triple-layer cuprate superconductor Bi2Sr2Ca2Cu3O10+δ. They find that, although the doping level of the inner CuO2 plane is extremely low in under-doped samples, the d-wave superconducting gap is enhanced at the antinode and persists well above Tc without a Fermi arc, indicating a “nodal metal”.
- Shin-ichiro Ideta
- Shintaro Adachi
- Atsushi Fujimori