First-principles calculations to investigate structural, electronic, magnetic mechanical, and thermal properties of half-Heusler alloys CoYGe (Y = Mn, Fe): using GGA and GGA+U potentials

In this work, we investigated the structural, electronic, magnetic, mechanical, and thermal properties of the CoYGe alloys. The negative cohesive energies for CoFeGe and CoMnGe affirm the chemical stability of these alloys. Electronic calculations using the GGA potential demonstrate a half-metallicity in both alloys with full spin polarization and total magnetic moments of 3μB\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mu _\textrm{B}$$\end{document} and 2μB\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mu _\textrm{B}$$\end{document}, respectively. These values agree well with those calculated by the Slater–Pauling rule. The Hubbard parameter U serves to diminish this characteristic in CoFeGe and entirely abolish it in CoMnGe, while concurrently augmenting its total magnetic moment. Additionally, an examination of the impact of compressive and tensile stress on spin polarization and magnetic moments is underway. The elastic and thermal properties of these alloys affirm their mechanical, dynamic, and thermodynamic stability. Consequently, these alloys are promising for potential applications in spintronics.