On the structure of the superconducting order parameter in high-temperature Fe-based superconductors

T.E. Kuzmicheva^a, b, A.V. Muratov^b, S.A. Kuzmichev^a, b, c, A.V. Sadakov^b, Yu.A. Aleshenko^b, V.A. Vlasenko^b, V.P. Martovitsky^b, K.S. Pervakov^b, d, Yu.F. Eltsev^b, V.M. Pudalov^b, e
^aLomonosov Moscow State University, Faculty of Physics, Leninskie Gory 1 build. 2, Moscow, 119991, Russian Federation
^bLebedev Physical Institute, Russian Academy of Sciences, Leninsky prosp. 53, Moscow, 119991, Russian Federation
^cLomonosov Moscow State University, Vorobevy Gory, Moscow, 119991, Russian Federation
^dInternational Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka str. 95, Wroclaw, 53-421, Poland
^eHSE University, ul. Myasnitskaya 20, Moscow, 101000, Russian Federation

This paper discusses the synthesis, characterization, and comprehensive study of Ba-122 single crystals with various substitutions and various T_c's. The paper uses five complementary techniques to obtain a self-consistent set of data on the superconducting properties of Ba-122. A major conclusion of the authors work is the coexistence of two superconducting condensates differing in the electron-boson coupling strength. The two gaps that develop in distinct Fermi surface sheets are nodeless in the k_xk_y-plane and exhibit s-wave symmetry, the two-band model represents a sufficient data description tool. A moderate interband coupling and a considerable Coulomb repulsion in the description of the two-gap superconducting state of barium pnictides favor the s⁺⁺-model.

Keywords: multi-gap superconductors, iron pnictides, specific heat, London penetration depth, Andreev spectroscopy, optics
PACS: 74.25.−q, 74.25.nd, 74.25.Ha, 74.45.+c, 74.70.Xa (all)
DOI: 10.3367/UFNe.2016.10.038002
URL: https://ufn.ru/en/articles/2017/4/g/
Web of Science

000405325500007
Scopus

2-s2.0-85025159254
ADS NASA

2017PhyU...60..419K
Citation: Kuzmicheva T E, Muratov A V, Kuzmichev S A, Sadakov A V, Aleshenko Yu A, Vlasenko V A, Martovitsky V P, Pervakov K S, Eltsev Yu F, Pudalov V M "On the structure of the superconducting order parameter in high-temperature Fe-based superconductors" Phys. Usp. 60 419–429 (2017)

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Received: 7th, December 2016, accepted: 5th, October 2016

Оригинал: Кузьмичёва Т Е, Муратов А В, Кузьмичёв С А, Садаков А В, Алещенко Ю А, Власенко В А, Мартовицкий В П, Перваков К С, Ельцев Ю Ф, Пудалов В М «О структуре параметра порядка в высокотемпературных сверхпроводниках на основе железа» УФН 187 450–462 (2017); DOI: 10.3367/UFNr.2016.10.038002