Abstract
We probe the local quasiparticles density of states in micron-sized single crystals by means of scanning tunnelling spectroscopy. Spectral features resemble those of cuprates, particularly a dip-hump-like structure developed at energies larger than the gap that can be ascribed to the coupling of quasiparticles to a collective mode, quite likely a resonant spin mode. The energy of the collective mode revealed in our study decreases when the pairing strength increases. Our findings support spin-fluctuation-mediated pairing in pnictides.
- Received 26 November 2009
DOI:https://doi.org/10.1103/PhysRevLett.105.167005
© 2010 The American Physical Society