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

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, T c. 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 T c ∼ 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 Δ(0) = 9.2 ± 0.5 meV, the ratio of 2Δ(0)/k B T c = 3.3 ± 0.2, and 0.010 < T c/T F < 0.014 (where T F is the Fermi temperature) and, thus, C2/m-SnH12 falls into unconventional superconductors band in the Uemura plot.

The dominance of non-electron–phonon charge carrier interaction in highly-compressed superhydrides

“…It should be mentioned that there are many theoretically possible mechanisms for charge carrier pairing in the condensed matter [11][12][13][14], and from the deduced power-law exponent presented herein, it is more likely that the primary mechanism is related to the electron-electron interaction. This finding is in good accord with the empirical finding that all hydrogen-rich superconductors are located [17,18,61,62] in the unconventional superconductors region of the Uemura plot [19,20].…”

High temperature superconductivity in the candidate phases of solid hydrogen

“…Because of the need for very dense k-and q-point samplings to obtain converged calculations (among other difficulties), the superconducting properties of the larger phases have remained elusive until recently. However, motivated by the developments in hydrogen-rich materials at high pressures that are breaking the records for superconducting temperatures [29][30][31][32][33][34][35][36][37], we recently reported an investigation into the superconducting properties of the C2/c-24 phase [38], and in this study, we focus on the Cmca-12 phase, as well as the Cmca-4 and I4 1 /amd-2 phases.…”

The Compliance of the Upper Critical Field in Magic-Angle Multilayer Graphene with the Pauli Limit

“…Deduced parameters are: 𝐴 = 3.26 ± 0.06 and 𝐵 = 0.74 ± 0.04. BCS weak-coupling limit IV (Carbotte 1990) linear fit weak-coupling BCS limit It should be mentioned that there are some approaches that link 2∆(0) k B T c and λ e−ph by utilizing more complicated approximating functions [3], or utilized double-valued functions [19] which approximates with better accuracy extended 2∆(0) k B T c vs. λ e−ph dataset (included data for hydrogen-rich superconductors [20,21]). However, herein, we used the linear approximate function (Equation ( 11)) to demonstrate that even this simplest assumption leads to the conclusion that the upper critical field data complies with Pauli limiting field in MATNG.…”