The effects of Cobalt doping on the structural, electronic, magnetic, and thermodynamic characteristics of the L10-FeNi alloy: First-principle calculations

Abstract

This study conducts a computational analysis employing density functional theory (DFT) to investigate the effects of Cobalt doping as substitutional defects on the structural, electronic, magnetic, and thermodynamic characteristics of the L 10− FeNi alloy. The aim of this study was to explore their potential applications as alternatives to rare-earth permanent magnets. Two types of substitutional Co-doping (ONi/OFe) in the Ni/Fe-site of the parent alloy have been investigated. The computed formation energy indicates that the incorporation of cobalt defects increases the structural stability of tetragonally distorted L10FeNi via Co-doping. The results we obtained demonstrate that the FeNi:Co (ONi) in the L10-structure has a large enhancement in magnetic moments and saturation magnetization (Ms), whereas for the FeNi:Co (OFe), has a small reduction in Ms. Furthermore, reducing the concentration of cobalt in L10 FeNi:Co alloys is advantageous in diminishing the volumetric thermal expansion coefficient, consequently lowering the Debye temperature and weakening atom interactions. Therefore, Co-substituted FeNi alloys hold promise as potential candidates for rare-earth-free permanent magnets.