2011/08/31 by Shin-Ming Huang, Chung‐Yu Mou, Chung-Yu Mou
Materials Science · Physics and Astronomy · #Antiferromagnetism #Condensed matter physics #Electronic structure #Frustration #Iron-based superconductors research #Physics #Rare-earth and actinide compounds #Spins #Superconductivity #Tight binding #Vacancy defect #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.84.184521
published as Physical Review B 84, 184521 (2011) · 9 pages, 4 figures
openalex publication_date 2011/11/16 · arxiv created 2011/11/24 · arxiv updated 2011/11/28 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We investigate the electronic structure of the ternary iron selenide KyFe1.6Se2 by considering the spatial symmetry of the √(5)\ifmmode×\else\texttimes\fi√(5) vacancy-ordered structure. Based on three orbitals of t2g, 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 that 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 KyFe1.6Se2. The spin fluctuations at q=(\ensuremathπ,\ensuremathπ) suggest that interblock fluctuations of spins might play an important role in the mechanism of superconductivity occurring in this system.