Thermoelectric modules are a promising approach to energy harvesting and efficient cooling. In addition to the longitudinal Seebeck effect, transverse devices utilizing the anomalous Nernst effect (ANE) have recently attracted interest. For high conversion efficiency, it is required that the material have a large ANE thermoelectric power and low electrical resistance, which lead to the conductivity of the ANE. ANE is usually explained in terms of intrinsic contributions from Berry curvature. Our observations suggest that extrinsic contributions also matter. Studying single-crystal manganese-bismuth (MnBi), we find a high ANE thermopower (∼10 μV/K) under 0.6 T at 80 K, and a transverse thermoelectric conductivity of over 40 A/Km. With insight from theoretical calculations, we attribute this large ANE predominantly to a new advective magnon contribution arising from magnon-electron spin-angular momentum transfer. We propose that introducing a large spin-orbit coupling into ferromagnetic materials may enhance the ANE through the extrinsic contribution of magnons.

热电模块是一种很有前途的能量收集和高效冷却方法。除了纵向塞贝克效应之外，利用异常能斯特效应 (ANE) 的横向装置最近引起了人们的兴趣。为了获得高转换效率，要求材料具有大的 ANE 热电功率和低电阻，这导致 ANE 的导电性。ANE 通常用 Berry 曲率的内在贡献来解释。我们的观察表明，外在贡献也很重要。研究单晶锰铋 (MnBi)，我们发现在 80 K 时低于 0.6 T 的高 ANE 热电势（~10 μV/K），以及超过 40 A/Km 的横向热电导率。结合理论计算，我们将这个大的 ANE 主要归因于由磁子 - 电子自旋 - 角动量转移引起的新平流磁子贡献。我们建议将大自旋轨道耦合引入铁磁材料可以通过磁振子的外在贡献增强 ANE。