Conductance asymmetry in point-contacts on epitaxial thin films of Ba(Fe0.92Co0.08)2As2

Mehta, Manan; Sheet, Goutam; Dikin, D. A.; Lee, S.; Bark, C. W.; Jiang, J.; Weiss, J. D.; Hellstrom, E. E.; Rzchowski, M. S.; Eom, C. B.; Chandrasekhar, V.
July 2010
Applied Physics Letters;7/5/2010, Vol. 97 Issue 1, p012503
Academic Journal
One of the most common observations in point-contact spectra on the recently discovered ferropnictide superconductors is a large conductance asymmetry with respect to voltage across the point-contact. In this paper, we show that the antisymmetric part of the point-contact spectrum between a silver tip and an epitaxial thin film of Ba(Fe0.92Co0.08)2As2 shows certain unique features that have an interesting evolution with increasing temperature up to a temperature far above the critical temperature Tc. We associate this observation with the existence of a gap above Tc that might originate from strong fluctuations of the phase of the superconducting order parameter.


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