Synthesis and Thermoelectric Characterization of Polycrystalline YbMnBi₂

YbMnBi₂ is a magnetic Weyl semimetal in which broken time-reversal symmetry and strong spin–orbit coupling generate a large net Berry curvature near the Fermi level ^[1]. This topological character gives rise to a pronounced anomalous Nernst effect (ANE) whose magnitude and sign are highly anisotropic, with published results in single-crystalline samples showing stark changes in ANE dependent on crystallographic orientation ^[2,3]. To explore whether this orientation dependence can be effectively “averaged out” while still maintaining a large ANE, we investigate polycrystalline YbMnBi₂, a form that has not yet been experimentally studied. Bulk samples were synthesized through high-energy ball milling of elemental Yb, Mn, and Bi followed by controlled annealing under inert atmosphere to ensure phase formation and minimize oxidation. We will present temperature- and magnetic field-dependence of both the Seebeck and Nernst effects, highlighting the relationship between synthesis conditions and the resulting magneto-thermoelectric response of polycrystalline YbMnBi₂.

[1] S. Borisenko et al., Nat. Commun. 10, 3424 (2019).

[2] Y. Pan et al., Nat. Mater. 21, 203 (2022).

[3] J. Wen et al., arXiv:2506.20721 (2025).