Harnessing Topological States for Enhanced Thermoelectricity in the Half-Heusler Compound FeMnTe

Topological thermoelectric materials have emerged as a promising class of multifunctional systems that combine band topology with feasible thermoelectric responses. This study elucidates the electronic, topological, and thermoelectric properties of the half-Heusler alloy FeMnTe using density functional theory in combination with a solution of Boltzmann transport equation. Our calculations reveal the ferromagnetic half-metallic behavior of FeMnTe with 100% spin polarization at the Fermi level and can be considered an ideal candidate for spintronics device applications due to its large semiconducting gap (1.24 eV) at the minority spin channel. We also demonstrate how the nontrivial topology manifested through nodal line and drumhead surface states give rise to significant Berry curvature distribution around EF, which in turn enriches anomalous transport properties. We observe a substantial intrinsic anomalous Hall conductivity (σxy) of 90 Ω–1 cm–1 at the Fermi level and an anomalous Nernst conductivity (αxy) that yields a significant value of 0.68 Am–1 K–1 at room temperature. Additionally, it showcases good thermoelectric responses such as enhanced electrical conductivity, Seebeck coefficient, and thermoelectric power factor. Contrary to other half-Heusler alloys, FeMnTe exhibits ultralow lattice thermal conductivity (<1 W/m-K) at higher temperatures (T > 900 K), which further leads to a thermoelectric figure of merit (ZT) ∼0.42. These findings emphasize the potential application of half-Heusler alloy FeMnTe toward futuristic quantum topological spintronic devices and energy-conversion technologies.