Open AccessSpin-fluctuation mechanism of superconductivity in Ba(Fe1-x Co x )2As2 ferropnictides
Author(s) -
A. E. Karakozov,
M. V. Magnitskaya,
A. V. Mikheenkov,
L. S. Kadyrov,
B. P. Gorshunov
Publication year - 2019
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1389/1/012066
Subject(s) - condensed matter physics , antiferromagnetism , superconductivity , pairing , spin (aerodynamics) , anisotropy , doping , physics , electron , band gap , isotropy , quantum mechanics , thermodynamics
Gap structure and spin-fluctuation pairing mechanism in the iron-based superconductors Ba(Fe 1-x Co x ) 2 As 2 is studied. We demonstrate that the overdoped compounds Ba(Fe 1-x Co x ) 2 As 2 have a three-gap structure with substantially different order parameters and a weak interband spin-fluctuation coupling. In the three-gap state of Ba(Fe 1-x Co x ) 2 As 2 , the anisotropic electronic gap has an intermediate value between two isotropic hole gaps. During transition to the optimal regime, the electron gap strongly increases (by a factor of two) and gets close to the largest hole gap value, while the electron gap anisotropy sharply decreases pointing to a strong increase in the interband interaction, with spin fluctuations accompanying the antiferromagnetic transition. The same two-gap state with close values of the electron and largest hole gaps is preserved even with further decrease in doping. The performed study shows that the spin-fluctuation pairing mechanism has a significant effect on doping evolution of the electron gap only. The doping evolution of the dominant hole gap in Ba(Fe 1- x Co x ) 2 As 2 is not directly related to the evolution of the spin fluctuations.