Eur. Phys. J. B (2015) 88: 150
https://doi.org/10.1140/epjb/e2015-60145-y

Regular Article

High-temperature superconductivity in two-band materials with interband pairing

National Research Nuclear University, Moscow Engineering Physics Institute, Kashirskoe sh.31, 115409 Moscow, Russia

^a e-mail: Eugen_mazur@mail.ru

Received: 24 February 2015
Published online: 10 June 2015

Abstract

Eliashberg theory is generalized with account of the specific properties of two-band electron-phonon (EP) systems. The superconducting transition temperature T_c is examined in two-band materials, one of the representatives of which are pnictides. The strong EP coupling and the pairing within the full width of the electron band and not only in a narrow region near the Fermi surface are taken into account. It is found that the effect of the pairing of electrons belonging to different bands is crucial to the appearance of high T_c in these materials. It is shown that the high T_c value in the materials, such as pnictides, is displayed with the use of a two-band spectral function of the EP interaction derived from calculations and from tunnel experiments. The existence of specific conditions for the high T_c appearance in the two-band materials is established.