Effective tight-binding model for the iron vacancy ordered A${}_y$FeSe${}_2$

Abstract

We investigate the electronic structure of the ternary iron selenide K${}_y$% Fe${}_{1.6}$Se${}_2$ by considering the spatial symmetry of the $\sqrt{5}$ vacancy ordered structure. Based on three orbitals of , which are believed to play major physics in iron-based superconductors, an effective two-dimensional tight binding Hamiltonian is constructed with the vacancy ordered structure being explicitly included. It is shown that the constructed band model, when combined with generalized Hubbard interactions, yields a spin susceptibility which exhibits both the block-checkerboard antiferromagnetism instability and the stripe antiferromagnetism instability. In particular, for large Hund's rule couplings, the block-checkerboard antiferromagnetism wins over the stripe antiferromagnetism, in agreement with the observation in experiments. We argue that such a model with correct symmetry and Fermi surface structures should be the starting point to model K${}_y$Fe${}_{1.6}$Se${}_2$. The spin fluctuations at $\mathbf{q}$=($\pi ,\pi$) suggest that interblock fluctuations of spins might play an important role in the mechanism of superconductivity occurring in this system.

9 pages, 4 figures

References in corpus (10)

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• Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides
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• d-wave pairing from spin fluctuations in the KxFe{2-y}Se2 superconductors
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• Ternary iron selenide K${}_{0.8}$Fe${}_{1.6}$Se${}_2$ is an antiferromagnetic semiconductor
• Cation vacancy order in the K0.8+xFe1.6-ySe2 system: five-fold cell expansion accommodates 20% tetrahedral vacancies
• Stripes, spin resonance and $d_{x^2-y^2}-$pairing symmetry in FeSe-based layered superconductors

Cited by in corpus (5)

• The Unexpected Properties of Alkali Metal Iron Selenide Superconductors
• Exotic magnetic order in the orbital-selective Mott regime of multiorbital systems
• Intrinsic high-temperature superconductivity in ternary iron selenides
• Band-filling and correlation controlling electronic properties and magnetism in K${}_x$Fe${}_{2-y}$Se${}_2$: A slave boson study
• Unconventional superconducting gap via spin fluctuations in iron-vacancy ordered A${}_y$Fe${}_{2-x}$Se${}_2$