Ab initio calculation of electronic band structure of Cd$_{1-x}$Fe$_x$Se

TL;DR

This study uses ab initio calculations to analyze how Fe doping affects the electronic band structure and band gap of CdSe, revealing that Fe concentration increases band gap and antiferromagnetic phase is more stable.

Contribution

First ab initio study of Fe-doped CdSe's electronic structure using DFT with Hubbard U, highlighting magnetic phase stability and band gap variation with Fe concentration.

Findings

Band gap increases with Fe concentration.

Antiferromagnetic phase is more stable.

Band gap values are approximately 1.77-1.92 eV depending on Fe content.

Abstract

The purpose of this work was to calculate the electronic band structure of Cd$_{1-x}$Fe$_x$Se. Ab-initio, calculations are performed in the Atomistix Toolkit program within the Density Functional Theory and Local Spin Density Approximation on Tight Tiger basis. We have used Hubbard U potential $U_{Fe} = 2.42$eV for 3d states for Fe ions. Super-cells of 8 and 64 atoms were constructed. After the construction of Cd$_{1-x}$Fe$_x$Se ($x=$ 6.25%; 25%) super-cells, atom relaxation and optimization of the crystal structure were carried out. Electronic band structure,and density of states were calculated, and total energy have been defined in antiferromagnetic and ferromagnetic phases. The band gap for the Cd$_{1-x}$Fe$_x$Se, $x=0.06$ in ferromagnetic phase is equal to $E_g=1.77$ eV, in antiferromagnetic phase $E_g=1.78$ eV. For $x=0.25$, $E_g=1.92$ eV. Antiferromagnetic phase considered more stable. Our calculations show that the band gap increases with the increases in Fe ion concentration.