Comparison of highly-compressed C2/m -SnH 12 superhydride with conventional superconductors.

Satterthwaite and Toepke (1970 Phys. Rev. Lett. 25 741) predicted high-temperature superconductivity in hydrogen-rich metallic alloys, based on an idea that these compounds should exhibit high Debye frequency of the proton lattice, which boosts the superconducting transition temperature, Tc. The idea has got full confirmation more than four decades later when Drozdovet al(2015 Nature 525 73) experimentally discovered near-room-temperature superconductivity in highly-compressed sulphur superhydride, H3S. To date, more than a dozen of high-temperature hydrogen-rich superconducting phases in Ba-H, Pr-H, P-H, Pt-H, Ce-H, Th-H, S-H, Y-H, La-H, and (La,Y)-H systems have been synthesized and, recently, Honget al(2021 arXiv:2101.02846) reported on the discovery ofC2/m-SnH12phase with superconducting transition temperature of Tc~ 70 K. Here we analyze the magnetoresistance data, R(T,B), ofC2/m-SnH12phase and report that this superhydride exhibits the ground state superconducting gap of Δ(0) = 9.2 ± 0.5 meV, the ratio of 2Δ(0)/kBTc= 3.3 ± 0.2, and 0.010 < Tc/TF< 0.014 (where TFis the Fermi temperature) and, thus,C2/m-SnH12falls into unconventional superconductors band in the Uemura plot.