Large Temperature‐invariant Anomalous Nernst Effect in Non‐collinear Antiferromagnet Mn 3 Pt

ABSTRACT The pursuit of next‐generation spintronic devices is pivoting toward noncollinear antiferromagnets (nc‐AFMs), their vanishing net magnetization and inherent ultrafast spin dynamics enable the development of faster and more energy‐efficient spintronic devices with strong resilience against external magnetic fields. Most importantly, their unique electronic and spin structures give rise to significant Berry curvature, leading to a significant magnetoelectric signal, such as the anomalous Nernst effect (ANE), even in the absence of sizable magnetization. Here, we report the discovery of a giant and remarkably temperature‐invariant ANE in high‐quality epitaxial Mn 3 Pt thin films with various compositions, which allows thermoelectric devices with a wide operating temperature window. Mn 3 Pt overwhelms other nc‐AFMs rivals with a significant ANE coefficient up to 0.71 µV/K at room temperature. Our combined experimental observation and theoretical calculations establish that the composition‐tunable Mn‐3d orbital states govern the Berry curvature landscape, responsible for this exceptional performance. This study highlights the composition tunability as a venue for applicable nc‐AFM spintronic devices.