Details

Autor(en) / Beteiligte

• Proslier, T.
• Zasadzinski, J. F.
• Cooley, L.
• Antoine, C.
• Moore, J.
• Norem, J.
• Pellin, M.
• Gray, K. E.

Titel

Tunneling study of cavity grade Nb: Possible magnetic scatteringat the surface

Ist Teil von

• Applied physics letters, 2008-05, Vol.92 (21), p.212505-212505-3

Ort / Verlag

American Institute of Physics

Erscheinungsjahr

2008

Quelle

AIP Scitation Journals Complete

Beschreibungen/Notizen

• Tunneling spectroscopy was performed on Nb pieces prepared by the same processes used to etch and clean superconducting radio frequency (SRF) cavities. Air exposed, electropolished Nb exhibited a surface superconducting gap Δ = 1.55 meV , which is characteristic of a clean, bulk Nb. However, the tunneling density of states (DOS) was significantly broadened. The Nb pieces, which were treated with the same mild baking used to improve the Q slope in SRF cavities, reveal a sharper DOS. Good fits to the DOS were obtained by using the Shiba theory, suggesting that magnetic scattering of quasiparticles is the origin of the gapless surface superconductivity and a heretofore unrecognized contributor to the Q -slope problem of Nb SRF cavities.