Butterfly angular patterns of planar Seebeck and Nernst effects in the Weyl semimetal NbP

Topological semimetals display unconventional magnetotransport arising from nontrivial band topology. Many topological semimetals exhibit extremely large, strongly angle-dependent magnetoresistance, which often exceed that of normal metals by orders of magnitude. We report butterfly-like angular patterns in the planar Seebeck and planar Nernst responses of single-domain NbP with ab, ac, and bc cuts. For ab-face samples, the angular responses are dominated by fourfold (4θ) harmonics, consistent with the C_4v symmetry of NbP. For ac and bc faces, the responses become predominantly twofold (2θ). Comparison across cuts, together with angle-resolved Shubnikov–de Haas oscillations, show that Fermi-surface anisotropy and the Berry-curvature dipole (BCD) jointly control the amplitude and phase of the planar thermoelectric responses. These measurements visualize the anisotropy of the Fermi surface and the BCD in NbP, and establish a crystal-symmetry-based framework for interpreting planar thermoelectric transport in topological semimetals.