Drag induced giant anomalous Nernst effect in Ferromagnetic MnBi

Anomalous Nernst effect (ANE) is the thermal equivalent to the Anomalous Hall effect (AHE). It has been observed in various materials and attributed to the Berry curvature of topological materials. In this talk, we present the observation of giant anomalous Nernst effect in MnBi single crystals. In addition to intrinsic contribution from the band structure, magnon drag also contributes to the anomalous Nernst signal in MnBi crystals, resulting in a giant anomalous Nernst thermopower of 18 μV/K at 0.6 T. At the same time, we also observe a magnon drag thermopower and positive magnetothermal conductivity. This magnon drag induce anomalous Nernst effect can be viewed as a self-spin Seebeck effect, which provides alternative path of understanding the electron magnon interaction.