Band structure of organic-ion-intercalated (EMIM)$_x$FeSe superconductor

TL;DR

This study investigates the electronic band structure and Fermi surface of the (EMIM)$_x$FeSe superconductor using density functional theory, revealing Fe-$d$ orbital dominance and organic cation-induced Fermi surface modifications.

Contribution

It provides the first detailed theoretical analysis of the band structure and Fermi surface of (EMIM)$_x$FeSe, highlighting the effects of organic cations on electronic properties.

Findings

Fe-$d$ orbitals dominate near the Fermi level

Organic cations shift the chemical potential

Small electron pockets appear in the Fermi surface

Abstract

The band structure and the Fermi surface of the recently discovered superconductor (EMIM)$_x$FeSe are studied within the density functional theory in the generalized gradient approximation. We show that the bands near the Fermi level are formed primarily by Fe-$d$ orbitals. Although there is no direct contribution of EMIM orbitals to the near-Fermi level states, the presence of organic cations leads to a shift of the chemical potential. It results in the appearance of small electron pockets in the quasi-two-dimensional Fermi surface of (EMIM)$_x$FeSe.