Electronic Structure of KFe$_2$Se$_2$ from First Principles Calculations

TL;DR

This study uses first-principles calculations to analyze the electronic structure and magnetic properties of KFe$_2$Se$_2$, revealing a stripe-like antiferromagnetic ground state and electronic features similar to heavily electron-doped Fe-based superconductors.

Contribution

It provides the first-principles analysis of KFe$_2$Se$_2$, identifying its magnetic ground state and electronic structure, and compares it to related iron-based superconductors.

Findings

Ground state is stripe-like antiferromagnetic with 2.26 μ_B on Fe.

Electronic states near E_F are dominated by Fe-3d orbitals.

Fermi surface resembles heavily electron-doped 11 systems.

Abstract

Electronic structure and magnetic properties for iron-selenide KFe$_2$Se$_2$ are studied by first-principles calculations. The ground state is stripe-like antiferromagnetic with calculated 2.26 $\mu_B$ magnetic moment on Fe atoms; and the $J_1$, $J_2$ coupling strengths are calculated to be 0.038 eV and 0.029 eV. The states around $E_F$ are dominated by the Fe-3d orbitals which hybridize noticeably to the Se-4p orbitals. While the band structure of KFe$_2$Se$_2$ is similar to a heavily electron-doped BaFe$_2$As$_2$ or FeSe system, the Fermi surface of KFe$_2$Se$_2$ is much closer to \fs11 system since the electron sheets around $M$ is symmetric with respect to $x$-$y$ exchange. These features, as well as the absence of Fermi surface nesting, suggest that the parental KFe$_2$Se$_2$ could be regarded as an electron over-doped 11 system with possible local moment magnetism.