Eur. Phys. J. B (2015) 88: 52
https://doi.org/10.1140/epjb/e2015-50616-6

Regular Article

Isotropic and anisotropic description of superconducting state in CaC6 compound

¹ Institute of Physics, Czȩstochowa University of Technology, Al. Armii Krajowej 19, 42-200 Czȩstochowa, Poland
² Institute of Physics, Jan Długosz University in Czȩstochowa, Al. Armii Krajowej 13/15, 42-200 Czȩstochowa, Poland

^a e-mail: d.szczesniak@ajd.czest.pl

Received: 10 September 2014
Received in final form: 9 January 2015
Published online: 18 February 2015

Abstract

The thermodynamic parameters of the superconducting state in CaC₆ have been determined in the framework of the isotropic and anisotropic Eliashberg formalism. The obtained results determine the anisotropy effect on the values of the thermodynamic functions. In particular, it has been found that the anisotropy of the electron-phonon coupling constant and the Coulomb pseudopotential significantly affects the order parameter and the wave function renormalization factor, which determines the electron effective mass. These results mean that anisotropy should be also visible in the total normalized density of states. In the case of the thermodynamic critical field, anisotropy lowers its value in the low-temperature area. On the other hand, it does not affect the specific heat jump at the critical temperature.