Double-valued strong-coupling corrections to Bardeen-Cooper-Schrieffer ratios

Abstract

Experimental discovery of near-room-temperature (NRT) superconductivity in highly-compressed H${}_3$S, LaH${}_1$${}_0$ and YH${}_6$ restores fundamental interest to electron-phonon pairing mechanism in superconductors. One of prerequisites of phonon-mediated NRT superconductivity in highly-compressed hydrides is strong electron-phonon interaction, which can be quantified by dimensionless ratios of Bardeen-Cooper-Schrieffer (BCS) theory vs $k{}_{B}T{}_c$/($\hslash$$\omega {}_l{}_n$), where Tc is the critical temperature and $\omega {}_l{}_n$ is the logarithmic phonon frequency (Mitrovic et al. 1984 Phys. Rev. B 29 184). However, all known strong-coupling correction functions for BCS ratios are applicable for $k{}_{B}T{}_c$/($\hslash$$\omega {}_l{}_n$)<0.20, which is not high enough $k{}_{B}T{}_c$/($\hslash$$\omega {}_l{}_n$) range for NRT superconductors, because the latter exhibit variable values of 0.13 < $k{}_{B}T{}_c$/($\hslash$$\omega {}_l{}_n$) < 0.32. In this paper, we reanalyze full experimental dataset (including data for highly-compressed H3S) and find that strong-coupling correction functions for the gap-to-critical-temperature ratio and for the specific-heat-jump ratio are double-valued nearly-linear functions of $k{}_{B}T{}_c$/($\hslash$$\omega {}_l{}_n$).

arXiv comment22 pages, 8 figures

References in corpus (20)

• Conventional superconductivity at 203 K at high pressures
• Superconductivity at 250 K in lanthanum hydride under high pressures
• Evidence for superconductivity above 260 K in lanthanum superhydride at megabar pressures
• A Perspective on Conventional High-Temperature Superconductors at High Pressure: Methods and Materials
• Hydrogen sulphide at high pressure: a strongly-anharmonic phonon-mediated superconductor
• Quantum Crystal Structure in the 250 K Superconducting Lanthanum Hydride
• Superconductivity at 161 K in Thorium Hydride $Th{H}_{10}$: Synthesis and Properties
• High-Temperature Superconductivity in Alkaline and Rare Earth Polyhydrides at High Pressure: A Theoretical Perspective
• Eliashberg Theory: a short review
• Superconducting Phase-Diagram of H3S under High Magnetic Fields
• Superconductivity of $La{H}_{10}$ and $La{H}_{16}$ polyhydrides
• Eliashberg theory of phonon-mediated superconductivity -- when it is valid and how it breaks down
• Quantitative analysis of nonadiabatic effects in dense H${}_3$S and PH${}_3$ superconductors
• Comparison of pressurized sulfur hydride with conventional superconductors
• High-temperature study of superconducting hydrogen and deuterium sulfide
• London penetration depth and thermal fluctuations in the sulphur hydride 203 K superconductor
• Classifying superconductivity in compressed H3S
• The road to room-temperature conventional superconductivity
• Isotope effect in superconducting lanthanum hydride under high compression
• Superconductivity of Bi-III phase of elemental Bismuth: insights from Muon-Spin Rotation and Density Functional Theory

Cited by in corpus (2)

• The compliance of the upper critical field in magic-angle multilayer graphene with the Pauli limit
• Comparison of highly-compressed C2/m-SnH12 superhydride with conventional superconductors