Anomalously high value of Coulomb pseudopotential for the \(\rm H_{5}S_{2}\) superconductor

The \({\rm H_{5}S_{2}}\) and \({\rm H_{2}S}\) compounds are the two candidates for the low-temperature phase of compressed sulfur-hydrogen system. We have shown that the value of Coulomb pseudopotential (\(\mu^{\star}\)) for \({\rm H_{5}S_{2}}\) (\(\left[T_{C}\right]_{\rm exp}=36\)~K and \(p=112\)~G...

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Bibliographic Details
Published in:arXiv.org 2018-07
Main Authors: Kostrzewa, Małgorzata, Szczęśniak, Radosław, Kalaga, Joanna K, Wrona, Izabela A
Format: Article
Language:English
Subjects:
Electron phonon interactions
Sulfur
Superconductivity
Online Access:Get full text
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Summary:The \({\rm H_{5}S_{2}}\) and \({\rm H_{2}S}\) compounds are the two candidates for the low-temperature phase of compressed sulfur-hydrogen system. We have shown that the value of Coulomb pseudopotential (\(\mu^{\star}\)) for \({\rm H_{5}S_{2}}\) (\(\left[T_{C}\right]_{\rm exp}=36\)~K and \(p=112\)~GPa) is anomalously high. The numerical results give the limitation from below to \(\mu^{\star}\) that is equal to \(0.402\) (\(\mu^{\star}=0.589\), if we consider the first order vertex corrections to the electron-phonon interaction). Presented data mean that the properties of superconducting phase in the \({\rm H_{5}S_{2}}\) compound can be understood within the classical framework of Eliashberg formalism only at the phenomenological level (\(\mu^{\star}\) is the parameter of matching the theory to the experimental data). On the other hand, in the case of \({\rm H_{2}S}\) it is not necessary to take high value of Coulomb pseudopotential to reproduce the experimental critical temperature relatively well (\(\mu^{\star}=0.15\)). In our opinion, \({\rm H_{2}S}\) is mainly responsible for the observed superconductivity state in the sulfur-hydrogen system at low temperature.
ISSN:2331-8422