NiVX (X=Si & Ge) Heuslerene: A ferromagnetic semiconductor for thermoelectric and spintronics applications through DFT study

The impact of ferromagnetic semiconductors on enhancing the thermoelectric properties of materials was investigated using novel Heuslerene (2D) NiVX (X = Si and Ge). In this study, both bulk and 2D nanosheets of NiVX (X = Si and Ge) were analyzed using the Quantum Espresso code with the ultrasoft pseudopotential approximation. A transition in lattice from FCC in the bulk form to hexagonal in the 2D nanosheets was observed, attributed to the change in dimensionality. The effects of confinement were examined through band structure and density of states, revealing that the nearly half-metallic ferromagnetic behavior of bulk NiVX (X = Si and Ge) transforms into ferromagnetic semiconductor behavior in the 2D nanosheets, with an intrinsic integer magnetic moment of 1.0 μ_B. The mechanical and thermodynamic stability of both bulk and 2D forms of NiVX (X = Si and Ge) was assessed, confirming their robustness.Thermoelectric properties were calculated and compared for bulk and 2D forms using the BoltzTrap code. The 2D nanosheets demonstrated significantly higher ZT values than their bulk counterparts, driven by an enhanced Seebeck coefficient and reduced electronic thermal conductivity. These findings highlight the superior thermoelectric performance of the 2D nanosheets.The combined ferromagnetic and thermoelectric properties of 2D NiVSi and NiVGe underscore their potential as versatile materials for future thermoelectric and spintronic applications.