Anomalous Nernst Effect and Transverse Thermoelectric Conversion in Co ₂ Mn Al‐Based Heusler Magnets

Abstract Topological Heusler ferromagnets have emerged as a promising material platform for realizing a large anomalous Nernst effect (ANE) due to their intrinsic Berry curvature. This work reports a significantly enhanced ANE in polycrystalline bulk Co 2 MnAl 1‐ x Si x , enabled by synergistic tuning of atomic ordering and Fermi level via Si substitution. A large anomalous Nernst thermopower of 4.9 µV K −1 and an anomalous Nernst conductivity of 1.46 A m −1 K −1 at 300 K are obtained in Co 2 MnAl 0.69 Si 0.31 . Furthermore, A centimeter‐sized bulk Nernst thermoelectric generator has been developed using Co 2 MnAl 0.69 Si 0.31 as the legs, which delivers an output voltage of 2.2 mV and a maximum power of 7.7 µW under a temperature difference of 15 K. These results highlight the potential of scalable, high‐performance polycrystalline topological magnets for transverse thermoelectric applications and pave the way for practical integration of ANE‐based devices.