Local quasiparticle density of states of superconducting SmFeAsO1 − xFx single crystals: Evidence for spin-mediated pairing

Y. FASANO; I. MAGGIO-APRILE; N. D. ZHIGADLO; S. KATRYCH; J. KARPINSKI; \O. FISCHER

PHYSICAL REVIEW LETTERS

AMER PHYSICAL SOC

Año: 2010 vol. 105 p. 167005 - 167008

0031-9007

We probe the local quasiparticles density of states in micron-sized SmFeAsO1-xFx 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.