Estimation of Intraband and Interband Relative Coupling Constants from Temperature Dependences of the Order Parameter for Two-Gap Superconductors

Journal of Superconductivity and Novel Magnetism. 2016. Vol. 29. No. 4. P. 1111–1116.

Kuzmichev S. A., Kuzmicheva T. E., Tchesnokov S. N., Pudalov V. M., Vasiliev A. N.

We present temperature dependences of the large and the small superconducting gaps measured directly by SnS-Andreev spectroscopy in various Fe-based superconductors and MgB2. The experimental L,S(T ) are wellfitted with a two-gap model based on Moskalenko and Suhl system of equations (supplemented with a BCSintegral renormalization). From the fitting procedure, we
estimate the key attribute of superconducting state — relative electron-boson coupling constants and eigen BCSratios for both condensates. Our results evidence for a driving role of a strong intraband coupling in the bands with the large gap, whereas interband coupling is rather weak for all the superconductors under study.

Ключевые слова: high temperature superconductors, iron pnictides, высокотемпературные сверхпроводники, пниктиды железа, Two-gap superconductivity, Andreev spectroscopy, двухщелевая сверхпроводимость, Андреевская спектроскопия