Evidence of Strong-Coupled Superconductivity in CaC6 from Tunneling Spectroscopy

C. Kurter, L. Ozyuzer, Daniel Mazur +5

Point-contact tunneling on CaC${}_6$ crystals reproducibly reveals superconducting gaps, $\Delta$, of 2.3$\pm$0.2 meV which are $\sim$~40% larger than earlier reports. That puts CaC${}_6$ i…