First Principles Investigation of FeCo Alloy: Electronic and Optical Properties Study

Ali Hossain,Rafiqul Islam

doi:10.11648/j.ep.20190301.11

Abstract

The ground state electronic structures and optical properties of FeCo alloy have been reported using plane wave ultrasoft pseudopotential based on spin polarized density functional theory through first principles study. The crystallographic structure of FeCo consists with body-centered cubic lattice that is described in space group Im-3m (229). The geometry is optimized with zero applied pressure and the optimized lattice constant is found to be 2.854A. The electronic energy bands represent the overlapped between valence and conductance electronic states and confirm zero forbidden gaps i.e. metallic nature of the FeCo alloy. The Fermi surfaces manifest the anisotropic features of electronic energy dispersion along the high symmetry directions (X-R-M-G-R) of the Brillouin zone. The total density of states arises from the contribution of the electronic states of Co and Fe atoms. The calculated spin magnetic moments of FeCo alloy is 1.26μB. The spin magnetic moments mainly come from the exchange interactions among electronic spins, which confirms the strong electron-electron interactions. Moreover, the optical properties are computed which also attest the metallic behavior of the material. The optical measurements indicate that FeCo alloy is an optically anisotropic material. The obtained loss spectrum reveals the plasmonic excitations that is important for many magneto-optical applications.

Highlights

The ferromagnetic bimetallic alloys have flourished as materials of extensive importance and many scopes in different fields of materials science and engineering
Based on density functional theory (DFT), the electronic structure calculation and structure optimization of FeCo alloy was performed by using first principles employed in CASTEP code [11]
The density of states reveals that the electronic properties of FeCo are mainly attained from the contribution of 3d electronic states of Fe and Co atoms

Summary

Introduction

The ferromagnetic bimetallic alloys have flourished as materials of extensive importance and many scopes in different fields of materials science and engineering. FeCo has greater attraction due to its unique physical and chemical properties Such as large value of saturation magnetization, high permeability, low coercivity, high curie temperature, low dielectric constant, excellent chemical stability and mechanical hardness, etc. For these properties, it is suitable for various chemical technological applications for instance, transformer core, electric motor, pole pieces, high temperature magnet, biomedicine, magnetic resonance imaging, hyperthermia-based therapy and specially data storage and so on. Spin polarized density functional theory (DFT) have been applied through generalized gradient approximation (GGA) approached to obtain the electronic structures and optical properties of FeCo alloy. The study of optical loss function as well as plasmonic excitations have been carried out that is expected for magneto-optical applications

Computational Modelling

Structure of Energy Bands

Optical Properties

Conclusions