Classifying hydrogen-rich superconductors

Abstract

The era of near-room-temperature superconductivity started after experimental discovery by Drozdov et al (2015 Nature 525 73) who found that compressed H3S exhibits superconducting transition at Tc = 203 K. To date, the record near-room-temperature superconductivity stands with another hydrogen-rich highly compressed compound, LaH10 (Somayazulu et al 2019 Phys. Rev. Lett. 122 027001), which has critical temperature of Tc>240 K. In this paper, we analyse available upper critical field, Bc2(T), data for LaH10 (Drozdov et al 2019 Nature 569 528) and report that this compound in all considered scenarios has the ratio of Tc to the Fermi temperature, Tf, 0.009 < Tc/Tf < 0.038, which is typical range for unconventional superconductors. In attempt to extend our finding, we examined experimental Bc2(T) data for superconductors in the palladium-hydrogen (PdHx) and thorium-hydrogen-deiterium (ThH-ThD) systems and surprisingly find that superconductors in both these systems also fall into unconventional superconductors band. Taking in account that H3S has the ratio of 0.012 < Tc/Tf < 0.039 (Talantsev 2019 Mod. Phys. Lett. B 33 1950195) we come to conclusion that in the Uemura plot all discovered to date hydrogen-rich superconductors, i.e., Th4H15-Th4D15, PdHx, H3S and LaH10 (in this list we do not include NbTiHx, PtHx, SiH4, and PH3 for which experimental data beyond Tc are unknown), lie in same band as all unconventional superconductors, particularly heavy fermions, fullerenes, pnictides, and cuprates, and former should be classified as a new class of unconventional superconductors.

25 pages, 2 figures, 3 tables, Supplementary Information

References in corpus (28)

• 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
• Hydrogen sulphide at high pressure: a strongly-anharmonic phonon-mediated superconductor
• A Sharp Peak of the Zero-Temperature Penetration Depth at Optimal Composition in BaFe2(As1-xPx)2
• High Pressure and Road to Room Temperature Superconductivity
• Universal self-field critical current for thin-film superconductors
• Superconducting Phase-Diagram of H3S under High Magnetic Fields
• Condensation, excitation, pairing, and superfluid density in high-$T_c$ superconductors: magnetic resonance mode as a roton analogue and a possible spin-mediated pairing
• Breakdown of the Migdal approximation at Lifshitz transitions with giant zero-point motion in H3S superconductor
• Effects of Neutron Irradiation on Pinning Force Scaling in State-of-the-Art Nb3Sn Wires
• Quantitative analysis of nonadiabatic effects in dense H${}_3$S and PH${}_3$ superconductors
• Comparison of pressurized sulfur hydride with conventional superconductors
• Superconducting materials classes: introduction and overview
• Thermodynamic parameters of single- or multi-band superconductors derived from self-field critical currents
• Fe-based superconducting thin films on metallic substrates: growth, characteristics and relevant properties
• On the origin of critical temperature enhancement in atomically-thin superconductors
• London penetration depth and thermal fluctuations in the sulphur hydride 203 K superconductor
• Superconductivity of platinum hydride
• Hole superconductivity in $H_{2}S$ and other sulfides under high pressure
• Classifying superconductivity in compressed H3S
• Classifying hydrogen-rich superconductors
• Destroying coherence in high temperature superconductors with current flow
• High Temperature Superconductivity: A Simple Model Exploiting Hydrogen Bonds
• A systematic study of the superconducting critical temperature in two and three dimensional tight-binding models: a possible scenario for superconducting H${}_3$S ?
• On the Calculation of the Inverse Isotope Effect in PdH(D): A Migdal-Eliashberg Theory Approach
• The onset of dissipation in high-temperature superconductors: magnetic hysteresis and field dependence
• On the fundamental definition of critical current in superconductors

Cited by in corpus (20)

• Nonstandard superconductivity or no superconductivity in hydrides under high pressure
• Classifying superconductivity in Moiré graphene superlattices
• Classifying hydrogen-rich superconductors
• Isotope effect in superconducting lanthanum hydride under high compression
• Resistive transition of hydrogen-rich superconductors
• Universal Fermi velocity in highly compressed hydride superconductors
• Classifying induced superconductivity in atomically thin Dirac-cone materials
• Classifying superconductivity in ThH-ThD superhydrides/superdeuterides
• The dominance of non-electron-phonon charge carrier interaction in highly-compressed superhydrides
• The electron-phonon coupling constant, the Fermi temperature and unconventional superconductivity in the carbonaceous sulfur hydride 190 K superconductor
• A-15 type superconducting hydride $L{a}_4{H}_{23}$: Nanograined structure with low strain, strong electron-phonon interaction, and moderate level of nonadiabaticity
• Unconventional superconductivity in highly-compressed unannealed sulphur hydride
• Quantifying the nonadiabaticity strength constant in recently discovered highly-compressed superconductors
• Comparison of highly-compressed C2/m-SnH12 superhydride with conventional superconductors
• High-$T$${}_{\text{C}}$ Superconductivity in Hydrogen Clathrates Mediated by Coulomb Interactions between Hydrogen and Central-Atom Electrons
• $d$-wave superconductivity as a model for diborides apart MgB${}_2$
• Superconductivity at ~70 K in Tin Hydride SnHx under High Pressure
• Structural and superconducting parameters of highly compressed sulfur
• Unconventional superconductivity in $\zeta$-phase of oxygen compressed to megabar pressure
• Characterization of near-room-temperature superconductivity in yttrium superhydrides