Exploring d–d and d–f Coupled Ba-Based Double Perovskites for Spintronic and Thermoelectric Applications: A First-Principles Study

Abstract

In this work, we present a first-principles investigation of the structural, electronic, magnetic, elastic, and thermoelectric properties of Ba-based double perovskites Ba₂MnTaO₆ and Ba₂TmTaO₆ using density functional theory. Both compounds are found to be structurally stable in the cubic phase. Ba₂MnTaO₆ exhibits half-metallic ferromagnetism with a high magnetic moment, indicating its suitability for spintronic applications. In contrast, Ba₂TmTaO₆ shows half-metallic behavior with nearly complete spin polarization, governed by the presence of localized f-electron states. Electronic structure analysis reveals strong hybridization between Mn-d and O-p states, while Tm-f states dominate near the Fermi level in Ba₂TmTaO₆. The calculated elastic constants confirm mechanical stability with anisotropic and brittle characteristics. Thermoelectric properties, evaluated using Boltzmann transport theory, demonstrate an increase in electrical conductivity and Seebeck coefficient with temperature, resulting in an enhanced power factor. These findings highlight the role of d–d and d–f interactions in tuning multifunctional properties, making Ba₂MnTaO₆ and Ba₂TmTaO₆ promising candidates for spintronic and thermoelectric applications.