Suppression of superconductivity by Neel-type magnetic fluctuations in the iron pnictides

الأصل · EN

Motivated by recent experimental detection of Neel-type ((π,π)) magnetic fluctuations in some iron pnictides, we study the impact of competing (π,π) and (π,0) spin fluctuations on the superconductivity of these materials. We show that, counter-intuitively, even short-range, weak Neel fluctuations strongly suppress the s⁺⁻ state, with the main effect arising from a repulsive contribution to the s⁺⁻ pairing interaction, complemented by low frequency inelastic scattering. Further increasing the strength of the Neel fluctuations leads to a low-Tc d-wave state, with a possible intermediate s+id phase. The results suggest that the absence of superconductivity in a series of hole-doped pnictides is due to the combination of short-range Neel fluctuations and pair-breaking impurity scattering, and also that Tc of optimally doped pnictides could be further increased if residual (π,π) fluctuations were reduced.