Description of the thermodynamic properties of BiH_{5} and BiH_{6} superconductors beyond the meanfield approximation
Abstract
The ab initio calculations suggest (Y. Ma et al.), that the highpressure (p = 200 GPa) superconducting state in BiH_{5} and BiH_{6} compounds characterizes with a high value of the critical temperature (T_{C} ∼ 100 K). Due to the large value of the electronphonon coupling constant (λ ∼ 1.2), the thermodynamic parameters of the superconducting phase in BiH_{5} and BiH_{6} have been determined beyond the meanfield approximation  in the framework of the Eliashberg equations formalism. We have calculated the dependence of the order parameter (Δ) and the wave function renormalization factor on the temperature. Then we have estimated the free energy difference between the superconducting state and the normal state, the thermodynamic critical field (H_{C}) and the specific heat of the superconducting state (C^{S}) and the normal state (C^{N}). The values of the dimensionless ratios R_{Δ} = 2 Δ(0) /k_{B}T_{C}, R_{C} = ΔC(T_{C}) /C^{N}(T_{C}) and R_{H} =T_{C}C^{N}(T_{C}) / H_{C}^{2} (0) are equal _{RΔBiH5} = 4.17 and _{RΔBiH6} = 4.20, _{RCBiH5} = 2.54 and _{RCBiH6} = 2.58, _{RHBiH5} = 0.146 and _{RHBiH6} = 0.146 respectively.
 Publication:

Solid State Communications
 Pub Date:
 September 2018
 DOI:
 10.1016/j.ssc.2018.05.009
 arXiv:
 arXiv:1803.00325
 Bibcode:
 2018SSCom.279...27J
 Keywords:

 Hydrogenrich materials;
 Highpressure effect;
 Electronphonon superconductivity;
 Eliashberg theory;
 Thermodynamic properties;
 Condensed Matter  Superconductivity
 EPrint:
 4 pages, 4 figures