The electron-phonon coupling constant, the Fermi temperature and unconventional superconductivity in a room-temperature superconductor carbonaceous sulfur hydride
Recently, Snider et al (2020 Nature 586 373-377) discovered room-temperature superconductivity in highly-compressed carbonaceous sulfur hydride, $H_x$$(S,C)_y$. In this paper we report results of analysis of experimental temperature dependent magnetoresistance data, R(T,B), reported by Snider et al. The analysis shows that $H_x$$(S,C)_y$ compound at pressure of P = 210 GPa has the electron-phonon coupling constant $\lambda$$_{e-ph}$ = 2.0 and the ratio of critical temperature, Tc, to the Fermi temperature, Tf, in the range of 0.010 < Tc/Tf < 0.018. These deduced values are very close to ones reported for $H_x$$S$ at P = 155-165 GPa. We also show that $H_x$$(S,C)_y$ sample (compressed at P = 267 GPa) with the record Tc = 285 K exhibits similar Tc/TF ratio. This means that in all considered scenarios the room-temperature superconductor $H_x$$(S,C)_y$ falls into unconventional superconductors band in the Uemura plot, where all other highly-compressed super-hydride/deuterides are located.