Identifying the `Fingerprint' of Antiferromagnetic Spin-Fluctuations on Iron-Pnictide Superconductivity
Abstract
Cooper pairing in the iron-based high-Tc superconductors is often conjectured to involve bosonic fluctuations. Among the candidates are antiferromagnetic spin-fluctuations and d-orbital fluctuations amplified by phonons. Any such electron-boson interaction should alter the electron's `self-energy', and then become detectable through consequent modifications in the energy dependence of the electron's momentum and lifetime. Here we introduce a theoretical/experimental approach aimed at identifying the relevant fluctuations of iron-based superconductors by measuring effects of their self-energy. We use quasiparticle interference (QPI) imaging techniques in LiFeAs to reveal strongly momentum-space anisotropic self-energy signatures that are focused along the Fe-Fe (interband scattering) direction, where the spin fluctuations of LiFeAs are concentrated. These effects coincide in energy with perturbations to the density-of-states N(\omega) usually associated with the Cooper pairing interaction. We show that all the measured phenomena comprise the predicted QPI `fingerprint' of a self-energy due to antiferromagnetic spin-fluctuations, thereby distinguishing them as the predominant electron-boson interaction.
Keywords
Cite
@article{arxiv.1402.3714,
title = {Identifying the `Fingerprint' of Antiferromagnetic Spin-Fluctuations on Iron-Pnictide Superconductivity},
author = {Milan P. Allan and Kyungmin Lee and Andreas W. Rost and Mark H. Fischer and Freek Massee and Kunihiro Kihou and Chul-Ho Lee and Akira Iyo and Hiroshi Eisaki and Tien-Ming Chuang and J. C. Davis and Eun-Ah Kim},
journal= {arXiv preprint arXiv:1402.3714},
year = {2015}
}