Superconducting phase diagram of H<sub>3</sub>S under high magnetic fields.

Mozaffari, Shirin; Sun, Dan; Minkov, Vasily S; Drozdov, Alexander P; Knyazev, Dmitry; Betts, Jonathan B; Einaga, Mari; Shimizu, Katsuya et al. · Nat Commun · 2019

basic_science · Level V

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Abstract

The discovery of superconductivity at 260 K in hydrogen-rich compounds like LaH<sub>10</sub> re-invigorated the quest for room temperature superconductivity. Here, we report the temperature dependence of the upper critical fields μ<sub>0</sub>H<sub>c2</sub>(T) of superconducting H<sub>3</sub>S under a record-high combination of applied pressures up to 160 GPa and fields up to 65 T. We find that H<sub>c2</sub>(T) displays a linear dependence on temperature over an extended range as found in multigap or in strongly-coupled superconductors, thus deviating from conventional Werthamer, Helfand, and Hohenberg (WHH) formalism. The best fit of H<sub>c2</sub>(T) to the WHH formalism yields negligible values for the Maki parameter α and the spin-orbit scattering constant λ<sub>SO</sub>. However, H<sub>c2</sub>(T) is well-described by a model based on strong coupling superconductivity with a coupling constant λ ~ 2. We conclude that H<sub>3</sub>S behaves as a strong-coupled orbital-limited superconductor over the entire range of temperatures and fields used for our measurements.