Inelastic neutron and x-ray scattering as probes of the sign structure of the Fe-pnictide superconducting gap

Abstract

Neutron spin-flip scattering observations of a resonance in the superconducting state is often taken as evidence of an unconventional superconducting state in which the gap changes sign $\Delta (k+Q)=-\Delta (k)$ for momentum transfers $Q$ which play an important role in the pairing. Recently questions regarding this identification for the Fe-pnictide superconductors have been raised and it has been suggested that $\Delta (k+Q)=\Delta (k)$. Here we propose that inelastic neutron or x-ray scattering measurements of the spectral weight of a phonon of momentum $Q$ can distinguish between these two pairing scenarios.

4 pages, 4 figures

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