Point-contact spectroscopy of iron-based layered superconductor LaO0.9F0.1-delta FeAs

We present point-contact spectroscopy data for junctions between a normal metal and the newly discovered F-doped superconductor LaO0.9F0.1-delta FeAs (F-LaOFeAs). A zero-bias conductance peak was observed and its shape and magnitude suggest the presence of Andreev bound states at the surface of F-LaOFeAs, which provides a possible evidence of an unconventional pairing symmetry with a nodal gap function. The maximum gap value Delta(0) approximate to 3.9 +/- 0.7meV was determined from the measured spectra, in good agreement with the recent experiments on specific heat and lower critical field. Copyright (c) EPLA, 2008.