Identifying the `Fingerprint' of Antiferromagnetic Spin-Fluctuations on Iron-Pnictide Superconductivity
Tien-Ming Chuang1*, Milan P. Allan2,3, Kyungmin Lee2, Andreas W. Rost2,4,5, Mark H. Fischer2, Freek Massee2,3, Kunihiro Kihou6,7, Chul-Ho Lee6,7, Akira Iyo6,7, Hiroshi Eisaki6,7, J.C. Davis2,3,4,8, Eun-Ah Kim2
1Institute of Physics, Academia Sinica, Taipei, Taiwan
2LASSP, Department of Physics, Cornell University, Ithaca, NY, United States of America
3CMPMS Department, rookhaven National Laboratory, Upton, NY, United States of America
4School of Physics and Astronomy, niversity of St Andrews, St Andrews, United Kingdom
5Department of Physics, The University of Tokyo, Tokyo, Japan
6Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
7Transformative Research-Project on Iron Pnictides, Tokyo, Japan
88 Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, United States of America
* presenting author:Tien-Ming Chuang,
Cooper pairing in iron-based superconductors(FeSC) is often conjectured to involve bosonic fluctuations, mediated by antiferromagnetic spin-fluctuations or orbital fluctuations amplified by phonons. By imaging Bogoliubov quasiparticle scattering interference (QPI) in LiFeAs, we explore the interband scattering conjectured to give rise to the observed antiferromagnetic spin-fluctuations as well as the electron-boson coupling signatures in the electronic self-energy. We show that the energy-momentum characteristics of these features are consistent with the antiferromagnetic spin fluctuation scenario for FeSC. In particular, the strong modification of the self-energy along the interband direction at the relevant energies in the superconducting state comprises the predicted QPI signatures due to antiferromagnetic spin-fluctuations.

Keywords: iron-based superconductors, scanning tunneling microscope