Probing the superconducting gap structure of (Li$_{1-x}$Fe$_x$)OHFeSe

Abstract

We report measurements of the London penetration depth [$Δλ(T)$] of the recently discovered iron-based superconductor (Li$_{1-x}$Fe$_x$)OHFeSe, in order to characterize the nature of the superconducting gap structure. At low temperatures, $Δλ(T)$ displays nearly temperature independent behavior, indicating a fully open superconducting gap. We also analyze the superfluid density $ρ_s(T)$ which cannot be well accounted for by a single-gap isotropic $s$-wave model but are consistent with either two-gaps, a model for the orbital selective $s\timesτ_3$ state or anisotropic $s$-wave superconductivity.

6 pages, 3 figures