Speaker
Description
Thermodynamic properties of superconducting state in the $\rm H_{5}S_{2}$ 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 $\rm H_{5}S_{2}$ 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 $\rm{H_{4}S_{3}}$ and ${\rm H_{2}S}$ compounds. The superconducting state of $\rm{H_{4}S_{3}}$ 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 ${\rm H_{2}S}$ compound has thermodynamic parameters with values close to the values determined for $\rm H_{5}S_{2}$ 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 ${\rm H_{2}S}$ compound, which is kinetically protected in the samples prepared at the low temperature. It should be emphasized that in the case of ${\rm H_{2}S}$ reproducing the experimental dependence of critical temperature on the pressure does not require anomalously high value of Coulomb pseudopotential.
