Point-contact spectroscopy of iron-based layered superconductor

National Laboratory for Superconductivity, Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences - P.O. Box 603, Beijing 100190, China

Corresponding author: lshan@aphy.iphy.ac.cn

Received: 12 May 2008
Accepted: 17 July 2008

Abstract

We present point-contact spectroscopy data for junctions between a normal metal and the newly discovered F-doped superconductor (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 ≈ 3.9±0.7  meV was determined from the measured spectra, in good agreement with the recent experiments on specific heat and lower critical field.