Doping Induced Magnetic and Electronic phase Transition in Ferrimagnetic Half-metallic Mn$_{4}$Al$_{11}$ Compound

TL;DR

This study uses density functional theory to explore how uniaxial strain and Ge doping affect the electronic and magnetic properties of Mn$_{4}$Al$_{11}$, revealing phase transitions and potential for material design in spintronics.

Contribution

It demonstrates how doping and strain can induce electronic and magnetic phase transitions in Mn$_{4}$Al$_{11}$, providing insights for tailoring material properties for technological applications.

Findings

Half-metallic gap collapses under >-2% strain but ferrimagnetism remains stable.

Ge substitution at specific sites induces a metal-insulator transition with a 0.14 eV gap.

Local electronic structure is significantly altered by Ge doping, affecting magnetic phases.

Abstract

The future of spintronic and semiconductor applications demands materials with tailored electronic and magnetic properties. This study uses density functional theory to investigate the electronic structure of the half-metallic compound Mn$_{4}$Al$_{11}$ under uniaxial strain and in its Ge-substituted derivatives. Strain analysis shows that although the half-metallic band-gap collapses under strain beyond $-2\%$, the ferrimagnetic character remains stable. Ge substitution at six inequivalent Al-sites in Mn$_{4}$Al$_{11}$ results in varying degrees of metallicity and magnetic properties. Substitution at Al$=(000)$ induces a metal-to-insulator transition with an indirect semiconducting gap of $0.14~ eV$. Bonding and hybridization analysis reveals that local Mn-Al interactions due to Ge substitution significantly modify the local electronic structure, causing both electronic and magnetic phase transitions. This work highlights the effectiveness of substitutional doping in tuning half-metallicity and magnetic properties in inorganic solids, enabling the design of materials for future technological applications.