Inelastic neutron scattering on iron-based superconductor BaFe2(As,P)2

Inelastic neutron scattering has been performed on powder sample of an iron-based superconductor BaFe2(As0.65P0.35)(2) with superconducting transition temperature (T-c) = 30 K, whose superconducting (SC) order parameter is expected to have line node. In the normal state, constant-E scan of dynamical structure factor, S(Q E), exhibits a peak structure centered at momentum transfer Q similar to 1.20 angstrom(-1), corresponding to antiferromagnetic wave vector. Below T-c, the redistribution of the magnetic spectral weight takes place, resulting in the formation of a peak at E similar to 12 meV and a gap below 6 meV. The enhanced magnetic peak structure is ascribed to the spin resonance mode, evidencing sign change in the SC order parameter similar to other iron-based high-T-c superconductors. It suggests that fully-gapped s(+/-) symmetry dominates in this superconductor, which gives rise to high-T-c (=30 K) despite the nodal symmetry. (C) 2011 Elsevier B.V. All rights reserved.