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MA: Fachverband Magnetismus

MA 26: Focus Session: Unconventional Thermoelectric Phenomena and Materials (joint session MA/TT)

MA 26.4: Invited Talk

Wednesday, March 20, 2024, 16:45–17:15, H 1058

Large anomalous Nernst thermoelectric performance in YbMnBi₂ — •Yu Pan^1,2, Congcong Le², Bin He², Sarah Watzman^3,4, Mengyu Yao², Johannes Gooth², Joseph Heremans³, Yan Sun², and Claudia Felser² — ¹Chongqing University, Chongqing, China — ²Max Planck Insitute for Chemical Physics of Solids, Dresden, Germany — ³The Ohio University, Columbus, USA — ⁴University of Cincinnati, Cincinnati, USA

The anomalous Nernst effect (ANE) have attracted increasing attention since the surge of topological semimetals, because the associated unique transverse geometry of ANE facilitates thermoelectric device fabrication. Topological ferromagnets with large Berry curvatures show large ANEs; however, they face drawbacks such as strong magnetic disturbances and low mobility due to high magnetization. Searching for materials with large ANE thermopower, low resistivity (high mobility), and low thermal conductivity are of great interest. It is found that YbMnBi₂, as a canted antiferromagnet, present a large ANE competitive to those of ferromagnets while with much lower resistivity and thermal conductivity. The canted spin structure of Mn guarantees a non-zero Berry curvature, but generates only a weak magnetization three orders of magnitude lower than that of general ferromagnets. The heavy Bi with a large spin-orbit coupling enables a large ANE and low thermal conductivity, whereas its highly dispersive p_x/y orbitals ensure low resistivity. These results suggest YbMnBi₂ as an excellent candidate for transverse thermoelectrics.

Keywords: thermoelectric; Berry curvature; antiferromagnet; anomalous Nernst effect; spin-orbit coupling