paper

Full Gap Superconductivity in Ba $_{0.6}$ K $_{0.4}$ Fe $_{2}$ As $_{2}$ Probed by Muon Spin Rotation

arXiv:0812.2069 · doi:10.1143/JPSJ.78.023710

Abstract

Superfluid density ( $n_{s}$ ) in the mixed state of an iron pnictide superconductor Ba $_{0.6}$ K $_{0.4}$ Fe $_{2}$ As $_{2}$ is determined by muon spin rotation for a sample with optimal doping ( $x = 0.4$ ). The temperature dependence of $n_{s}$ is perfectly reproduced by the conventional BCS model for s-wave paring, where the order parameter can be either a single-gap with $I^ = 8.35 (6)$ meV [ $2 I^/ k_{B} T_{c} = 5.09 (4)$ ], or double-gap structure with $I^_{1} = 12$ meV (fixed) [ $2 I^_{1} / k_{B} T_{c} = 7.3$ ] and $I^_{2} = 6.8 (3)$ meV [ $2 I^_{2} / k_{B} T_{c} = 4.1 (2)$ ]. The latter is consistent with the recent result of angle-resolved photo-emssion spectroscopy. The large gap parameters ( $2 I^/ k_{B} T_{c}$ ) indicate extremely strong coupling of carriers to bosons that mediate the Cooper pairing.

4 pages, 3 figures

Full Gap Superconductivity in Ba0.6​K0.4​Fe2​As2​ Probed by Muon Spin Rotation

Abstract

Full Gap Superconductivity in Ba $_{0.6}$ K $_{0.4}$ Fe $_{2}$ As $_{2}$ Probed by Muon Spin Rotation