Band Structure of Organic-Ion-Intercalated (EMIM)xFeSe Superconductor.

Maxim M Korshunov,Lyudmila V Begunovich

doi:10.3390/ma15051856

Abstract

The band structure and the Fermi surface of the recently discovered superconductor (EMIM)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)FeSe.

Highlights

We have studied the electronic structure of (EMIM)x FeSe using the state-of-art density functional theory in the generalized gradient approximation
Fe-d orbitals form the bands near the Fermi level similar to other
Orbitals of EMIM do not affect the low-energy states directly; the presence of EMIM leads to the shift of the chemical potential that results in the transformation of the Fermi surface topology and appearance of small electron pockets around X-point in (EMIM)2 Fe18 Se18 in contrast to FeSe with the similar crystal structure

Summary

Introduction

FeSe was placed on the cathode (negatively charged electrode) where the redox reaction takes place using the electrons transferred through an external circuit from the anode. It is not clear yet which of the chemical species gain electrons. To make a first step towards understanding the nature of superconductivity in (EMIM)x FeSe, here we calculate its band structure and Fermi surface using density functional theory (DFT). Band structures of (EMIM) Fe18 Se18 and FeSe with the same crystal structure are similar, their Fermi surfaces are different.

Computation Details and Crystal Structure

Results and Discussion

Conclusions