Classifying superconductivity in compressed H3S

Abstract

The discovery of high-temperature superconductivity in compressed [Formula: see text] by Drozdov and co-workers [A. Drozdov et al., Nature 525 (2015) 73] heralded a new era in superconductivity. To date, the record transition temperature of [Formula: see text] stands with another hydrogen-rich compound, [Formula: see text] [M. Somayazulu et al., Phys. Rev. Lett. 122 (2019) 027001] which becomes superconducting at pressure of [Formula: see text]. Despite very intensive first-principle theoretical studies of hydrogen-rich compounds compressed to megabar level pressure, there is a very limited experimental dataset available for such materials. In this paper, we analyze the upper critical field, [Formula: see text], data of highly compressed [Formula: see text] reported by Mozaffari and co-workers [S. Mozaffari et al., LA-UR-18-30460. https://doi.org/10.2172/1481108 ] by utilizing four different models of [Formula: see text]. As the result, we find that the ratio of superconducting energy gap, [Formula: see text], to the Fermi energy, [Formula: see text], in all considered scenarios is [Formula: see text], with respective ratio of [Formula: see text] to the Fermi temperature, [Formula: see text], [Formula: see text]. These characterize [Formula: see text] as unconventional superconductor and places it on the same trend line in [Formula: see text] versus [Formula: see text] plot, where all unconventional superconductors are located.