Metal hydrogen sulfide superconducting temperature

Abstract

Éliashberg theory is generalized to the electronphonon (EP) systems with the not constant density of electronic states. The phonon contribution to the anomalous electron Green's function (GF) is considered. The generalized Éliashberg equations with the variable density of electronic states are resolved for the hydrogen sulphide SH 3 phase under pressure. The dependence of both the real and the imaginary part of the order parameter on the frequency in the SH 3 phase is obtained. The Tc = 177 K value in the hydrogen sulfide SH 3 phase at the pressure P = 225 GPa has been defined. The results of the solution of the Eliashberg equations for the Im-3m (170 GPa), Im-3m (200 GPa) and R3m (120 GPa) phases are presented. A peak value Tc = 241 K of the superconducting transition temperature has been predicted. The aim of present work is to derive the generalized Éliashberg equations for the precise Tc calculation in the materials with the strong EP interaction. Such a formalism should allow one a quantitative calculation and prediction of the superconducting properties and Tc in the different phases of the hydrogen sulfide [1, 2], as well as in the high-temperature materials with the EP mechanism of superconductivity, which will be discovered in the near future. We take into account all the features of the frequency behavior of the spectral function of the EP interaction, the behavior of the electronic density of states N 0 (ω) and the specific properties of matter in which the superconducting state is established. The derivation of the Éliashberg equations [13,14] is performed anew on a more rigorous basis, leading to the new terms in the equations for the order parameter. We have taken into account the Coulomb contribution to the order parameter despite the smallness of the Coulomb pseudopotential µ * ≈ 0.1 in the hydrogen sulfide SH 3 phase compared with the significant constant λ ∼ 2.273 of the EP interaction in the sulfide phase. Near Tc the product Reφ (︀ z ′ )︀ Imφ (︀ z ′ )︀ tends to zero for all values of the argument. We obtain omitting the small quantities ImZ (ω), Reχ (ω), Imχ (ω) the following non-linear Unauthenticated Download Date | 5/12/18 10:05 AM Keywords

Compressed H3S: inter-sublattice Coulomb coupling in a high-TCsuperconductor

“…Currently available theoretical results for T C of H 3 S from the phononic theories mentioned in section 1 are represented in figure 1 by various gray symbols [2,4,8,10,11,13,14,[16][17][18]; the legend indicates the crystal structure where given. In addition to its dependence on pressure and structure, calculated T C is seen to vary anneal, green circles with center dot, and < RT anneal, blue circles (from [1,5,6]).…”

“…Temperature dependence of critical fields H CF and associated magnetization extrema M CF are shown in figure 2, Variation of measured T C of H 3 S with applied pressure P for ⩾RT (room temperature) anneal, green circles with center dot, and <RT anneal, blue circles (from [1,5,6]). Gray symbols are various theoretical calculations denoted as (D) [2], (E) [4], (P) [8], (A) [10], (K) [11], (G) [13], (F) [14], (S) [16], (К) [17], and (J) [18]; structure indicated where available. Red square symbol (H) corresponds to T C0 from this work.…”

A Schematic Two Overlapping-Band Model for Superconducting Sulfur Hydrides: The Isotope Mass Exponent

“…e Eliashberg equations are strong-coupling extensions to the original BCS theory. Calculations with this theory can be found where they study the high T c in sulfur hydride as a result of the variability in the DOS within the band [30]. Many theoretical calculations based on Eliashberg theory for H 3 S can be found in the literature and also in [31], where the authors also provide an optical spectroscopy study for this material and found spectroscopic evidence that the superconducting mechanism in H 3 S is due to the electron-phonon interaction.…”

A model for superconducting sulfur hydrides

“…The Eliashberg equations are extensions for strong coupling of the original BCS theory. Calculations with this theory can be found where they study the high-T c in sulfur hydride as a result of the variability in the density of states in the band [25]. Many theoretical calculations based on Eliashberg theory for H 3 S, can be found in the literature among them in [26], where the authors also provide an optical spectroscopy study for this material and found spectroscopy evidence that the superconducting mechanism in H 3 S is the electron-phonon interaction.…”