Comparison of highly-compressed C2/m-SnH12 superhydride with conventional superconductors

TL;DR

This paper analyzes the superconducting properties of the C2/m-SnH12 superhydride, revealing its unconventional superconducting characteristics and providing detailed measurements of its superconducting gap and transition temperature.

Contribution

It presents the first detailed analysis of the superconducting gap and properties of C2/m-SnH12, highlighting its unconventional superconductivity compared to conventional superconductors.

Findings

Superconducting gap Δ(0) = 9.2 meV

Ratio 2Δ(0)/k_B Tc = 3.3

Tc/Tf ratio indicates unconventional superconductivity

Abstract

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 Drozdov et 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, Hong et al (2021 arXiv:2101.02846) reported on the discovery of C2/m-SnH12 phase with superconducting transition temperature of Tc ~ 70 K. Here we analyse the magnetoresistance data, R(T,B), of C2/m-SnH12 phase and report that this superhydride exhibits the ground state superconducting gap of $\Delta$(0) = 9.2 meV, the ratio of 2$\Delta$(0)/k$_B$Tc = 3.3, and 0.010 < Tc/Tf < 0.014 (where Tf is the Fermi temperature) and, thus, C2/m-SnH12 falls into unconventional superconductors band in the Uemura plot.