Investigation of the electronic, magnetic, and thermoelectric characteristics of the transition metal-based double perovskites Ba2XNbO6 (X = V, Cr, Mn, and Fe) for spintronic applications

Abstract

Spin-polarized materials with high Curie temperatures are emerging aspirants for spintronics. In the present work, we conduct first-principles calculations using the WIEN2k code to examine the structural, electronic, magnetic, and thermoelectric properties of Ba₂XNbO₆ (X = V, Cr, Mn, and Fe). The thermodynamic stability is confirmed by the negative enthalpies of formation and the structural stability by the tolerance factor. The range of Curie temperatures (T_c) from 289 K to 325 K for the studied materials allows for room-temperature ferromagnetism. Inferring from their spin-polarized band structures, Ba₂VNbO₆ and Ba₂MnNbO₆ have half-metallic ferromagnetism, and Ba₂CrNbO₆ and Ba₂FeNbO₆ have ferromagnetic semiconductor behavior. The calculated exchange and crystal field energies and exchange constants reveal dominant spin–orbit coupling rather than magnetic ion clustering. The total magnetic moment analysis demonstrates that the magnetic moment ranges from 2.0µ_B to 5.00µ_B for the Fe-based compounds, reflecting the gradual addition of electrons to the 3d orbitals, and its distribution to non-magnetic sites confirms the exchange of electrons. Additionally, these compounds show great potential in thermoelectrics. Ba₂VNbO₆ reached a power factor of 8.60 W mK⁻² because of its good electrical conductivity and moderate Seebeck coefficient. These results underscore that substituting the B-site elements in Ba₂XNbO₆ (X = V, Cr, Mn, and Fe) can improve the spintronic and thermoelectric properties by modifying the electronic structure, magnetic behavior, and measurable thermoelectric power.