A Three-Dimensional Tight-Binding Model and Magnetic Instability of KFe2e2

Da-Yong Liu; Ya-Min Quan; Zhi Zeng; Liang-Jian Zou

doi:10.1016/j.physb.2012.01.101

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arXiv · 1106.3485

A Three-Dimensional Tight-Binding Model and Magnetic Instability of KFe2e2

Da-Yong Liu·Ya-Min Quan·Zhi Zeng·Liang-Jian Zou

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Abstract

For a newly discovered iron-based high T_c superconducting parent material KFe2Se2, we present an effective three-dimensional five-orbital tight-binding model by fitting the band structures. The three t2g-symmetry orbitals of the five Fe 3d orbitals mainly contribute to the electron-like Fermi surface, in agreement with recent angle-resolved photoemission spectroscopy experiments. To understand the groundstate magnetic structure, the two- and three-dimensional dynamical spin susceptibilities within the random phase approximation are investigated. It obviously shows a sharp peak at wave vector $\mathbf{Q}$ $\thicksim$ ($π$, $π$), indicating the magnetic instability of {\it N$\acute{e}$el}-type antiferromagnetic rather than ($π$/2, $π$/2)-type antiferromagnetic ordering. While along $\emph{c}$ axis, it exhibits a ferromagnetic coupling between the nearest neighboring FeSe layers. The difference between the present results and the experimental observation in KxFe2-ySe2 is attributed to the presence of Fe vacancy in the latter.

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Da-Yong Liu, Ya-Min Quan, Zhi Zeng, Liang-Jian Zou. 2011-06-17. A Three-Dimensional Tight-Binding Model and Magnetic Instability of KFe2e2. https://doi.org/10.1016/j.physb.2012.01.101

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