APS March Meeting 2023

Large anomalous Nernst effect in canted antiferromagnet YbMnBi2

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A large anomalous Nernst effect (ANE) is crucial for thermoelectric energy conversion applications because the associated unique transverse geometry facilitates module 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. $ YbMnBi_2 $, as a canted antiferromagnet, surprisingly shows a large ANE conductivity of $ ~10 A m{^−1}$ \ $K{^−1} $ that surpasses large values observed in other ferromagnets (3–5 A m−1 K−1). 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 px/y orbitals ensure low resistivity. The high anomalous transverse thermoelectric performance and extremely small magnetization make $ YbMnBi_2 $ an excellent candidate for transverse thermoelectrics.