Seebeck and Anomalous Nernst Effects in Chern Insulator NiCl₃ Monolayer

Transverse thermoelectricity, enabled by the Nernst effect, presents a promising alternative to conventional Seebeck-effect-based energy harvesting by leveraging perpendicular heat-to-current conversion. A critical challenge lies in identifying materials that simultaneously exhibit nontrivial band topology and room-temperature magnetic order. Here, we demonstrate that the Chern insulator NiCl 3 monolayer fulfills these requirements. This material features a Dirac spin-gapless state with ferromagnetic ordering at a 400 K Curie temperature. Considering spin-orbit coupling, the NiCl 3 monolayer turns into an intrinsic Chern insulator ( C = −1) with a non-trivial band gap of ∼7 meV. Using the Fukui-Hatsugai-Suzuki method, we predict a large anomalous Nernst conductivity of 100 µ V/K at 100 K (for τ = 1 fs), originating from the Berry curvature near the Fermi level. These unique properties suggest that the NiCl 3 monolayer has potential for use in transverse thermoelectric applications.