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 shows certain unique features that have an interesting evolution with increasing temperature up to a temperature far above the critical temperature . We associate this observation with the existence of a gap above that might originate from strong fluctuations of the phase of the superconducting order parameter.
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.© 2010 American Institute of Physics.
2010
American Institute of Physics
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