Giant Magneto‐Seebeck Effect in a Van Der Waals Antiferromagnet

ABSTRACT Harnessing the spin degrees of freedom offers unprecedented opportunities to engineer electronic band structures and transport behaviors, laying the foundation for spintronic devices. Particularly, the magneto‐Seebeck effect provides direct insight into the interplay among spin order, electron and heat transport. Here, we observe an unconventional giant magneto‐Seebeck effect in the van der Waals (vdW) antiferromagnet (Fe,Co) 3 GaTe 2 , reaching −74% at 2 K. First‐principles calculations reveal that the antiferromagnet‐to‐ferromagnet transitions in (Fe,Co) 3 GaTe 2 trigger pronounced band re‐construction, significantly modulating the density of states near the Fermi level. We further perform magneto‐electric transport experiments and observe positive magneto‐resistance in (Fe,Co) 3 GaTe 2 , a result that validates our theoretical predictions. This work reveals a giant magneto‐Seebeck effect in a vdW antiferromagnet and uncovers the critical role of spin‐state‐dependent electronic band modulation in vdW magnets, providing a novel strategy for designing high‐performance thermoelectric materials via spin state engineering.