Ultrahigh anomalous Nernst thermopower and thermal Hall angle in YbMnBi2
J. S. Wen, Kaustuv Manna, Dung Vu, Subhadeep Bej, Yu Pan, Claudia Felser, Brian Skinner, Joseph P. Heremans
Abstract
Thermoelectrics (TEs) are solid-state devices that can realize heat-electricity conversion. Transverse TEs require materials with a large Nernst effect, which typically requires a strong applied magnetic field. However, topological materials with magnetic order offer an alternative pathway for achieving large Nernst via the anomalous Hall effect and the accompanying anomalous Nernst effect (ANE) that arise from band topology. Here, we show that YbMnBi2 with a low Hall density and a chemical potential near the Weyl points has, to the best of our knowledge, the highest ANE-dominated Nernst thermopower of any magnetic material, with Syx around 110 μV K-1 (T = 254 K, 5 T ≤ |μ0H | ≤ 9 T applied along the spin canting direction), due to the synergism between classical contributions from filled electron bands, large Hall conductivity of topological origin, and large resistivity anisotropy. An appreciable thermal Hall angle of 0.02 <∇yT/∇xT (−9 T) < 0.06 was observed (40 K < T < 310 K). Thermoelectric devices enable heat-electricity conversion, but achieving a large Nernst effect typically requires strong magnetic fields. Here, the authors demonstrate that YbMnBi2, with its unique band topology and magnetic order, exhibits a remarkably high anomalous Nernst thermopower among magnetic materials, offering a promising route for efficient transverse thermoelectric applications.