Evidence for Two-Band Superconductivity from Break-Junction Tunneling onMgB2

H. Schmidt, J. F. Zasadzinski, K. E. Gray, D. G. Hinks
2002 Physical Review Letters  
Superconductor-insulator-superconductor tunnel junctions have been fabricated on MgB2 that display Josephson and quasiparticle currents. These junctions exhibit a gap magnitude, Delta~2.5 meV, that is considerably smaller than the BCS value, but which clearly and reproducibly closes near the bulk Tc. In conjunction with fits of the conductance spectra, these results are interpreted as direct evidence of two-band superconductivity.
doi:10.1103/physrevlett.88.127002 pmid:11909494 fatcat:ualptzpfnfasnfj4w7hcklyx5e