Orbital-selective superconductivity in the nematic phase of FeSe*

The considerations of the orbital-selective Mott physics in the normal state [1,2] motivated the theoretical proposal for orbital-selective pairing [3]. The experimental evidence for the latter has come from both the iron pnictides [4] and iron selenides [5]. We study the superconductivity in the presence of nematic order in a multi-orbital model with frustrated spin-exchange interactions [6]. We found that the electron correlation effects amplified by the nematic order [7] give rise to an enhanced orbital-selective pairing. The latter produces a large gap anisotropy on the Fermi surface which naturally explains the experimental observations.

[1] R. Yu and Q. Si, PRL 110, 146402 (2013); PRB 84, 235115 (2011).
[2] M. Yi et al., PRL 110, 067003 (2013).
[3] R. Yu, J.-X. Zhu and Q. Si, PRB 89, 024509 (2014).
[4] C. Zhang et al., PRL 111, 207002 (2013).
[5] P. O. Sprau et al., Science 357, 75 (2017).
[6] H. Hu, R. Yu, E. M. Nica, J.-X. Zhu, and Q. Si, arXiv:1805.05915.
[7] R. Yu, J.-X. Zhu, and Q. Si, PRL in press, arXiv:1803.01733.