Deviating band symmetries and many-body interactions in a model hole-doped iron pnictide superconductor

Citation Wray, L. et al. " Deviating Band Symmetries and Many-body Interactions in a Model Hole-doped Iron Pnictide Superconductor. Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. We present a polarization-resolved study of the low-energy band structure in the optimally doped iron pnictide superconductor Ba 0.6 K 0.4 Fe 2 As 2 (T c = 37 K) using angle-resolved photoemission spectroscopy. Polarization-contrasted measurements are used to identify and trace all three low-energy holelike bands predicted by local density approximation (LDA) calculations. The photoemitted electrons reveal an inconsistency with LDA-predicted symmetries along the-X high-symmetry momentum axis, due to unexpectedly strong rotational anisotropy in electron kinetics. We evaluate many-body effects such as Mott-Hubbard interactions, which are likely to underlie the anomaly, and discuss how the observed deviations from LDA band structure affect the energetics of iron pnictide Cooper pairing in the hole-doped regime.