$Ab~initio$ studies of Co$_2$FeAl$_{1-x}$Si$_x$ Heusler alloys

TL;DR

This study uses density functional theory to analyze how silicon alloying affects the structural stability electronic properties and hyperfine fields of Co2FeAl1-xSix Heusler alloys, revealing Si's role in stabilizing structure and modifying electronic states.

Contribution

It provides the first detailed theoretical analysis of Si's impact on the structural and electronic properties of Co2FeAl1-xSix Heusler alloys using all-electron calculations.

Findings

Si stabilizes the L2_1 structure against disorder

Silicon shifts the Fermi level into the minority spin gap

Hyperfine field on Co increases with Si concentration

Abstract

We present results of extensive theoretical studies of Co$_2$FeAl$_{1-x}$Si$_x$ Heusler alloys, which have been performed in the framework of density functional theory employing the all-electron full-potential linearized augmented plane-wave scheme. It is shown that the Si-rich alloys are more resistive to structural disorder and as a consequence Si stabilizes the $L2_1$ structure. Si alloying changes position of the Fermi level, pushing it into the gap of the minority spin-band. It is also shown that the hyperfine field on Co nuclei increases with the Si concentration, and this increase originates mostly from the changes in the electronic density of the valence electrons.