Onsager Reciprocal Relation between Anomalous Transverse Coefficients of an Anisotropic Antiferromagnet

Whenever two irreversible processes occur simultaneously, time-reversal symmetry of microscopic dynamics gives rise, on a macroscopic level, to Onsager's reciprocal relations, which impose constraints on the number of independent components of any transport coefficient tensor. Here, we show that in the antiferromagnetic YbMnBi2, which displays a strong temperature-dependent anisotropy, Onsager's reciprocal relations are strictly satisfied for anomalous electric (σijA) and anomalous thermoelectric (αijA) conductivity tensors. In contradiction with what was recently reported by Pan et al. [Nat. Mater. 21, 203 (2022)NMAACR1476-112210.1038/s41563-021-01149-2], we find that σijA(H)=σjiA(-H) and αijA(H)=αjiA(-H). This equality holds in the whole temperature window irrespective of the relative weights of the intrinsic or extrinsic mechanisms. The αijA/σijA ratio is close to kB/e at room temperature but peaks to an unprecedented magnitude of 2.9kB/e at ∼150 K, which may involve nondegenerate carriers of small Fermi surface pockets.