Non-BCS thermodynamic properties of H2S superconductor

The present paper determines the thermodynamic properties of the superconducting state in the H2S compound. The values of the pressure from 130 GPa to 180 GPa were taken into consideration. The calculations were performed in the framework of the Eliashberg formalism. In the first step, the experimental course of the dependence of the critical temperature on the pressure was reproduced: T-C is an element of < 31, 88 > K, whereas the Coulomb pseudopotential equal to 0.15 was adopted. Next, the following quantities were calculated: the order parameter at the temperature of zero Kelvin (Delta(0)), the specific heat jump at the critical temperature (Delta C(T-C) equivalent to C-S (T-C) - C-N (T-C)), and the thermodynamic critical field (H-C(0)). It was found that the values of the dimensionless ratios: R-Delta equivalent to 2 Delta(0)/k(B)T(C), R-C equivalent to Delta C(T-C)/C-N(T-C), and R-H equivalent to TCCN(T-C)/H-C(2)(0) deviate from the predictions of the BCS theory: R-Delta is an element of < 3.64, 4.16 >, R-C is an element of < 1.59, 2.24 >, and R-H is an element of < 0.144, 0.163 >. Generalizing the results on the whole family of the HnS-type compounds, it was shown that the maximum value of the critical temperature can be equal to similar to 290 K, while R-Delta, R-C and R-H adopt the following values: 6.53, 3.99, and 0.093, respectively. (C) 2015 Elsevier B.V. All rights reserved.