$H_{3}S$ is a high-$\kappa$ superconductor with columnar pinning defects

Abstract

Recently, the existence of superconductivity in ${\mathrm{H}}_3\mathrm{S}$ and other high-pressure hydrides is called into question, because of some flawed magnetic measurements. In Ref.[1] the SCPC model is proposed, where strong pinning of vortices is due to long columnar defects in ${\mathrm{H}}_3\mathrm{S}$ - with lengths $\mathrm{L}$ of the order of vortex lengths ${\mathrm{L}}_{\mathrm{v}}$. Two relevant type of experiments in magnetic fields are explained by this model: (1) Reduction (with respect to standard superconductors) of the thermal broadening of resistance ($TBR$) in magnetic field $\mathrm{h}=H/{\mathrm{H}}_{c2}$, $\delta {\mathrm{t}}_{\mathrm{c}}(\mathrm{h})$, is governed by the small parameter $\mathrm{C}=$${\xi }_0/\mathrm{L}$. The $TBR$ measurements give, that in ${\mathrm{H}}_3\mathrm{S}$ there is a large shift of the irreversible line ${\mathrm{B}}_{\mathrm{irr}}(\mathrm{T})$ towards the ${\mathrm{B}}_{c2}(\mathrm{T})$ line. (2) In ZFC (zero field cooled) experiments on penetration of the magnetic field ($PMF$) in ${\mathrm{H}}_3\mathrm{S}$ [3], the latter reaches the center of a superconducting disk at much larger external fields, i. e. for ${\mathrm{B}}_0\gg {\mathrm{B}}_{c1}$. The later is due to the pronounced pinning of vortices, but not to the Meissner effect. The calculated $\mathrm{T}$- dependence of the penetrated, perpendicular ${\mathrm{B}}_{\perp }(\mathrm{T})$ and parallel ${\mathrm{B}}_{\parallel }(\mathrm{T})$, magnetic field into the sample is in satisfactory agreement with the experimental results for ${\mathrm{H}}_3\mathrm{S}$ in [3], where ${\mathrm{B}}_{\perp }>{\mathrm{B}}_{\parallel }$. Problems related to measurements of the Meissner effect in ${\mathrm{H}}_3\mathrm{S}$ are also discussed. The SCPC model, applied on the bulk ${\mathrm{H}}_3\mathrm{S}$ sample, predicts, that the latter is a high-$\kappa$ superconductor.

12 pages, 7 figures. Typos corrected, on p.10 "${\lambda }_0$ too large" is replaced by "${\lambda }_0$ too small"