Slope of the upper critical field at $T_{c}$ in two-band superconductors with non-magnetic disorder: $s_{++}$ superconductivity in $\textrm{Ba}_{1-x}\textrm{K}_{x}\textrm{Fe}_{2}\textrm{As}_{2}$

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Hauptverfasser: Prozorov, R., Kogan, V. G., Konczykowski, M., Tanatar, M. A.
Format: Preprint
Veröffentlicht: 2023
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author Prozorov, R.
Kogan, V. G.
Konczykowski, M.
Tanatar, M. A.
author_facet Prozorov, R.
Kogan, V. G.
Konczykowski, M.
Tanatar, M. A.
contents A recent theory of the disorder-dependent slope of the upper critical field, $H_{c2}$, at the superconducting transition temperature, $T_{c}$, is extended to multiband superconductors aiming at iron-based superconductors, considering two constant gaps of different magnitude and, potentially, different signs. The result shows that there is only a narrow domain inside the $s_{\pm}$ pairing state where the slope increases with the increase of transport (non-magnetic) scattering rate, $P$. In most phase space, the slope should decrease in an $s_{\pm}$ state and increase in the $s_{++}$ pairing state. The experiment shows that in an archetypal iron-based superconductor, $\textrm{Ba}_{1-x}\textrm{K}_{x}\textrm{Fe}_{2}\textrm{As}_{2}$ (BaK122), non-magnetic disorder induced by electron irradiation increases the slope $S$ across the superconducting ``dome,'' at different $x$. This implies that $\textrm{Ba}_{1-x}\textrm{K}_{x}\textrm{Fe}_{2}\textrm{As}_{2}$ is likely an $s_{++}$ superconductor with two (or more) gaps of different magnitudes. This work reopens a decade-long discussion of the nature of the superconducting order parameter in iron pnictides.
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id arxiv_https___arxiv_org_abs_2306_08703
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Slope of the upper critical field at $T_{c}$ in two-band superconductors with non-magnetic disorder: $s_{++}$ superconductivity in $\textrm{Ba}_{1-x}\textrm{K}_{x}\textrm{Fe}_{2}\textrm{As}_{2}$
Prozorov, R.
Kogan, V. G.
Konczykowski, M.
Tanatar, M. A.
Superconductivity
Materials Science
A recent theory of the disorder-dependent slope of the upper critical field, $H_{c2}$, at the superconducting transition temperature, $T_{c}$, is extended to multiband superconductors aiming at iron-based superconductors, considering two constant gaps of different magnitude and, potentially, different signs. The result shows that there is only a narrow domain inside the $s_{\pm}$ pairing state where the slope increases with the increase of transport (non-magnetic) scattering rate, $P$. In most phase space, the slope should decrease in an $s_{\pm}$ state and increase in the $s_{++}$ pairing state. The experiment shows that in an archetypal iron-based superconductor, $\textrm{Ba}_{1-x}\textrm{K}_{x}\textrm{Fe}_{2}\textrm{As}_{2}$ (BaK122), non-magnetic disorder induced by electron irradiation increases the slope $S$ across the superconducting ``dome,'' at different $x$. This implies that $\textrm{Ba}_{1-x}\textrm{K}_{x}\textrm{Fe}_{2}\textrm{As}_{2}$ is likely an $s_{++}$ superconductor with two (or more) gaps of different magnitudes. This work reopens a decade-long discussion of the nature of the superconducting order parameter in iron pnictides.
title Slope of the upper critical field at $T_{c}$ in two-band superconductors with non-magnetic disorder: $s_{++}$ superconductivity in $\textrm{Ba}_{1-x}\textrm{K}_{x}\textrm{Fe}_{2}\textrm{As}_{2}$
topic Superconductivity
Materials Science
url https://arxiv.org/abs/2306.08703