Year: 2011
Type: article
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 $\sqrt{5}\ifmmode\times\else\texttimes\fi{}\sqrt{5}$ vacancy-ordered structure. Based on three orbitals of ${t}_{2g}$, 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 K${}_{y}$Fe${}_{1.6}$Se${}_{2}$. The spin fluctuations at $\mathbf{q}=(\ensuremath{\pi},\ensuremath{\pi}$) suggest that interblock fluctuations of spins might play an important role in the mechanism of superconductivity occurring in this system.
Source: Physical Review B
Authors: Shin-Ming Huang, Chung-Yu Mou
Language: Latvian
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2076463232