CEC-ICMC 2019 - Abstracts, Timetable and Presentations

M2Po2A-03 [27]: The issue of induction the superconducting state in selected compressed sulfur and hydrogen systems

23 Jul 2019, 13:30

2h

Level 6, Cryo Expo Exhibit Hall

Poster Presentation M2Po2A - Thin Films, Artificial Structures, Flux Pinning

Speaker

Ms Małgorzata Kostrzewa (Institute of Physics, Jan Długosz University in Częstochowa)

Description

Thermodynamic properties of superconducting state in the ${\mathrm{H}}_5{\mathrm{S}}_2$ system were analyzed precisely. The calculations were carried out in two cases: included the lowest-order vertex correction-scheme VCEE (Vertex Corrected Eliashberg Equations), on the other hand we get the model without the vertex corrections, the so-called CEE scheme (Classical Eliashberg Equations). It has been proven that under pressure 112 GPa , the superconducting state induced in the ${\mathrm{H}}_5{\mathrm{S}}_2$ compound is characterized by anomalously high value of Coulomb pseudopotential (also after taking into account the vertex corrections to the electron-phonon interaction). The analysis contains also the parameters study of superconducting state, that is induced in the ${\mathrm{H}}_4{\mathrm{S}}_3$ and ${\mathrm{H}}_2\mathrm{S}$ compounds. The superconducting state of ${\mathrm{H}}_4{\mathrm{S}}_3$ compound is the BCS type, however it cannot be equated with the experimentally measured low-temperature superconducting state in the compressed hydrogen sulfide, since it has a very low critical temperature. On the other hand, has been shown that the superconducting state in ${\mathrm{H}}_2\mathrm{S}$ compound has thermodynamic parameters with values close to the values determined for ${\mathrm{H}}_5{\mathrm{S}}_2$ in the CEE (Classical Eliashberg Equations) scheme and is not the state of BCS type. In our opinion, experimentally was observed the superconducting state in the ${\mathrm{H}}_2\mathrm{S}$ compound, which is kinetically protected in the samples prepared at the low temperature. It should be emphasized that in the case of ${\mathrm{H}}_2\mathrm{S}$ reproducing the experimental dependence of critical temperature on the pressure does not require anomalously high value of Coulomb pseudopotential.

Presentation materials

Kostrzewa.pdf