In-plane p-wave coherence length in iron-based superconductors

High-temperature superconductivity in iron-based layered compounds discovered by Hosono group (Kamihara et al 2006 J. Am. Chem. Soc. 128 10012) is fascinating physical phenomenon which still has many unanswered questions. One of these questions is the superconducting gap symmetry in iron-based superconductors (IBS), for which the most agreed concept is multiple-band $s$-wave symmetry. Recently, an alternative concept of single-band $p$-wave symmetry has been proposed. To disprove/reaffirm the latter concept, in this paper we analyse temperature dependent in-plane coherence length in FeSe, FeSe1-xTex, Ba(Fe1-x(Co,Ni)x)2As2 and Ca10(Pt4As8)((Fe,Pt)2As2)5 in order to extract the gap-to-critical-temperature ratio, 2$\Delta$(0)/$k$$_B$$T$$_c$, and the specific-heat-jump ratio, $\Delta$C/C,in these compounds. In the result, we report that deduced ratios are in a good agreement with the concept of single-band $p$-wave superconductivity in these materials.