Structural, electronic and magnetic properties of feni alloys

The structural, electronic, magnetic, and thermodynamic properties of Llo-FeNi alloys and their cobalt-doped counterparts have been investigated to assess the impact of cobalt as substitutional defects. This study aims to explore potential alternatives for more efficient permanent magnets in advanced applications. The research was conducted within the framework of Density Functional Theory (DFT), where doping was performed at two different sites within the parent alloy: nickel substitution (ON) and iron substitution (OFC). The computed lattice parameters showed excellent agreement with previous studies, while the formation energy calculations indicated that cobalt doping enhances the structural stability of the alloy. Furthermore, the results revealed that the FeNi:Co (ONi) alloy exhibits a significant increase in magnetic moments and saturation magnetization (Ms), whereas FeNi:Co (Ore) shows a slight decrease in Ms. From a thermodynamic perspective, the study was conducted using the quasi-harmonic Debye model, demonstrating that reducing cobalt concentration leads to a decrease in both the volumetric thermal expansion coefficient and the Debye temperature. Based on these findings, cobalt-substituted FeNi alloys emerge as promising candidates for rare-earth-free permanent magnets