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

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Milestone experimental discovery of superconductivity above 200 K in highly-compressed sulphur hydride by Drozdov et al (Nature 525, 73 (2015)) sparked experimental and theoretical investigations of metallic hydrides. Since then, a dozen of superconducting binary and ternary polyhydrides have been discovered. For instance, there are three superconducting polyhydrides of thorium: Th4H15, ThH9, and ThH10 and four polyhydrides of yttrium: YH4, YH6, YH7, YH9. In addition to binary and ternary hydrogen-based metallic compounds, recently Eremets et al (arXiv:2109.11104) reported on the metallization of hydrogen, which is in remarkable agreement with first-principles calculated e-ph(174 GPa) = 1.75 (Semenok et al, Materials Today 33, 36 (2020)). Deduced e-ph(172 GPa) = 1.90 ± 0.02 for Im-3m-YD6 is also in excellent agreement with first-principles calculated e-ph(165 GPa) = 1.80 (Troyan et al, Advanced Materials 33, 2006832 (2021)). And finally, we deduced T(402 GPa) = 727 ± 6 K for hydrogen phase III which implies that e-ph(402 GPa) ≤ 1.7 in this metal.The electron-phonon coupling constant and the Debye temperature in polyhydrides of thorium, hexadeuteride of yttrium, and metallic hydrogen phase III

Section: Resultsmentioning

confidence: 99%

“…Webb [64] reported temperature dependence of the resistivity, (T), of ultra-pure elemental niobium which exhibited the residual resistance ratio of…”

Section: Elemental Niobiummentioning

confidence: 99%

Section: Elemental Niobiummentioning

confidence: 99%

“…It also should be mentioned that in Ref. 67 we fitted the same (T) dataset to more advanced model [64,[69][70][71][72]:…”

mentioning

confidence: 99%

“…ferromagnetic metals and materials [69,71], highly-compressed iron [69], and some other materials [64,69,72], were analysed by using advanced Bloch-Grüneisen equation (Eq. 12).…”

mentioning

confidence: 99%

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The electron–phonon coupling constant and the Debye temperature in polyhydrides of thorium, hexadeuteride of yttrium, and metallic hydrogen phase III

Talantsev

2021

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The superconducting transition temperatures of C–S–H based on inter-sublattice S−H4-tetrahedron electronic interactions

Harshman

Fiory²

2022

Significant characteristics of the superconducting transitions reported for carbonaceous sulfur hydride [Snider et al., Nature 585, 373 (2020)] are the exceptionally abrupt onset temperatures and their marked increase toward room temperature at high pressure. Theoretical and experimental studies addressing the superconducting composition and structure have thus far returned mixed results. One possibility, consistent with the experimentally suggested stoichiometry of CSH x , is the theoretically-discovered compressed I 3m CSH 7 structure [Sun et al., Phys. Rev. B 101, 174102 (2020)], which comprises a sublattice similar to Im m H 3 S with CH 4 intercalates. Positing an electronic genesis of the superconductivity, a model is presented in analogy with earlier work on superconductivity in Im m H 3 S, in which pairing is induced via purely electronic Coulomb interactions across the mean distance ζ between the S and H 4 tetrahedra enclosing C. Theoretical superconducting transition temperatures for I 3m CSH 7 are derived as T C0 = (2/3) 1/2  1/2 /aζ, where  = 1247.4 Å 2 K is a universal constant,  is the participating charge fraction, and a is the lattice parameter. Analysis suggests persistent bulk superconductivity with a pressure-dependent , increasing from  = 3.5, determined previously for Im m H 3 S, to  = 7.5 at high pressure owing to additionally participating C-H bond electrons. With a and ζ determined by theoretical structure, T C0 = 283.6  3.5 K is predicted at 267  10 GPa, in excellent agreement (within uncertainty) with the corresponding experimental T C = 287.7  1.2 K. Pressure-induced variations in  combined with experimental uncertainties in pressure yield overall average (T C  T C0 ) = (0.8  3.5) K.

Quantifying interaction mechanism in infinite layer nickelate superconductors

Talantsev

2023

The connection between the long-range antiferromagnetic order in cuprates and the high-temperature superconductivity is a scientific problem that has yet to be solved after nearly four decades. The properties and difficulties of describing nickelate superconductors are similar to those of cuprates. Recently, Fowlie et al. [Nat. Phys. 18, 1043 (2022)] aimed to detect the antiferromagnetic order in R1−xSrxNiO2 (R = Nd, Pr, La; x ∼ 0, 0.2) films by using the muon spin rotation (μSR) technique. The research group reported the presence of short-range antiferromagnetic order in every nickelate studied. Here, our goal was to prove that this interaction is present in the nickelate films. We did this by analyzing the temperature dependent resistivity, ρ(T), data from the research group. Global ρ(T) data fits to the advanced Bloch–Grüneisen model showed that each of the R1−xSrxNiO2 compounds can be characterized by a unique power-law exponent, p (where p = 2 for the electron–electron scattering, p = 3 for the electron–magnon scattering, and p = 5 for the electron–phonon scattering), and global characteristic temperature, Tω (which has the meaning of the Debye temperature at p = 5). We found that p = 2.0 in Nd- and Pr-based compounds and p = 1.3 for La-based compounds. The latter value does not have any interpretation within established theoretical models. We also analyzed ρ(T) data for Nd1–xSrxNiO2(0.125≤x≤0.325) reported by Lee et al. [Nature 619, 288 (2023)]. Our analysis of nickelates led us to conclude that a new theoretical model is needed to describe ρ(T) in materials exhibiting a short-range antiferromagnetic order.