Common ($\pi$,$\pi$) Band Folding and Surface Reconstruction in FeAs-Based Superconductors

Abstract

High resolution angle-resolved photoemission spectroscopy (ARPES) measurements are carried out on CaKFe${}_4$As${}_4$, KCa${}_2$Fe${}_4$As${}_4$F${}_2$ and (Ba${}_{0.6}$K${}_{0.4}$)Fe${}_2$As${}_2$ superconductors. Clear evidence of band folding between the Brillouin zone center and corners with a ($\pi$,$\pi$) wave vector has been found from the measured Fermi surface and band structures in all the three kinds of superconductors. A dominant $\sqrt{2}\times \sqrt{2}$ surface reconstruction is observed on the cleaved surface of CaKFe${}_4$As${}_4$ by scanning tunneling microscopy (STM) measurements. We propose that the commonly observed $\sqrt{2}\times \sqrt{2}$ reconstruction in the FeAs-based superconductors provides a general scenario to understand the origin of the ($\pi$,$\pi$) band folding. Our observations provide new insights in understanding the electronic structure and superconductivity mechanism in iron-based superconductors.

arXiv comment15 pages, 4 figures

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Cited by in corpus (4)

• Unconventional density waves and superconductivities in Fe-based superconductors and other strongly correlated electron systems
• ARPES Detection of Superconducting Gap Sign in Unconventional Superconductors
• Genuine Electronic Structure and Superconducting Gap Structure in (Ba${}_{0.6}$K${}_{0.4}$)Fe${}_2$As${}_2$ Superconductor
• Second magnetization peak, anomalous field penetration, and Josephson vortices in KCa${}_2$Fe${}_4$As${}_4$F${}_2$ bilayer pnictide superconductor