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

Yongqing Cai; Tao Xie; Huan Yang; Dingsong Wu; Jianwei Huang; Wenshan Hong; Lu Cao; Chang Liu; Cong Li; Yu Xu; Qiang Gao; Taimin Miao; Guodong Liu; Shiliang Li; Li Huang; Huiqian Luo; Zuyan Xu; Hongjun Gao; Lin Zhao; X. J. Zhou

doi:10.1088/0256-307x/38/5/057404

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arXiv · 2104.13745

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

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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.

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Yongqing Cai, Tao Xie, Huan Yang, Dingsong Wu, Jianwei Huang, Wenshan Hong, Lu Cao, Chang Liu, Cong Li, Yu Xu, Qiang Gao, Taimin Miao, Guodong Liu, Shiliang Li, Li Huang, Huiqian Luo, Zuyan Xu, Hongjun Gao, Lin Zhao, X. J. Zhou. 2021-04-28. Common ($\pi$,$\pi$) Band Folding and Surface Reconstruction in FeAs-Based Superconductors. https://doi.org/10.1088/0256-307x%2F38%2F5%2F057404

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