Abstract
We present a microscopic study of the nuclear magnetic relaxation rate 1/T 1 based on the five-orbital model for iron-based superconductors. We mainly discuss the effect of the inelastic quasi-particle damping rate γ due to many-body interaction on the size of the coherence peak, for both s ++ and s ±-wave superconducting states. We focus on Ba(Fe 1xCo x) 2As 2, and systematically evaluate γ in the normal state from the experimental resistivity, from optimally to overdoped compounds. Next, γ in the superconducting state is calculated microscopically based on second-order perturbation theory. In optimally doped compounds (T c30K), it is revealed that the coherence peak on 1/T 1T is completely suppressed due to large γ for both s ++ and s ±-wave states. On the other hand, in heavily overdoped compounds with T c<10K, the coherence peak could appear for both pairing states, since γ at T c is quickly suppressed in proportion to . By making careful comparison between theoretical and experimental results, we conclude that it is difficult to discriminate between s ++ and s ±-wave states from the present experimental results.
Original language | English |
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Article number | 084006 |
Journal | Superconductor Science and Technology |
Volume | 25 |
Issue number | 8 |
DOIs | |
Publication status | Published - Aug 2012 |
ASJC Scopus subject areas
- Ceramics and Composites
- Condensed Matter Physics
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry