Unidirectional magnetoresistance, or electric magnetochiral anisotropy (eMChA), is a nonlinear magnetotransport effect emerging in noncentrosymmetric conductors. This phenomenon manifests as a resistance $R$ change proportional to the first power of both the electric current $\mathbf{I}$ and applied magnetic field $\mathbf{B}$. The eMChA contribution $\mathrm{\Delta }R\left(B\right)/R\left(0\right)$ takes distinct forms: (i) a chiral term, $2\chi \mathbf{I}·\mathbf{B}$, and (ii) a polar term, $2\gamma \mathbf{I}·(\mathbf{P}\times \mathbf{B})$, where $\mathbf{P}$ denotes the electric polarization and $\chi$ and $\gamma$ represent the respective eMChA coefficients. In Fontana et al. [Phys. Rev. Lett. 135, 106602 (2025)], we provided empirical evidence that the eMChA in the conduction band of tellurene is polar $(\chi =0,$ $\gamma \ne 0)$ and showed that it emerges from the quantum metric dipole associated with its Weyl node and from the lone pair polarization $\mathbf{P}$. Here, we extend this study to the valence band of tellurene, where the eMChA is commonly assumed to be chiral $(\chi \ne 0,\gamma =0)$. We show that a finite polar coefficient $\gamma \ne 0$ also emerges naturally through a downfolding procedure, in which remote Weyl-node-containing bands induce momentum-space gradients of the quantum metric in the low-energy levels, activating finite metric dipoles. Combining semiclassical Boltzmann transport with a $\mathbf{k}·\mathbf{p}$ description of tellurene, our numerical calculations agree quantitatively with doping $\left(\mu \right)$ dependent second-harmonic measurements of the longitudinal voltage $V_{\parallel }^{2\omega }\left(\mu \right)$ in perpendicular field. The combined chiral and polar characters $(\chi \ne 0,\gamma \ne 0)$ of the eMChA in tellurene also explains the shift in the angular $\left(\varphi \right)$ dependence of $V_{\parallel }^{2\omega }\left(\varphi \right)$ for in plane fields. Our results demonstrate that the polar eMChA can arise in topologically trivial bands through multiband effects and establish tellurene as a platform for quantum-geometric rectification in both electron and hole regimes.

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• Electrical conductivity
• Geometric & topological phases
• Magnetoresistance
• Topological phases of matter
• Noncentrosymmetric materials
• Weyl semimetal
• Boltzmann theory
• k dot p method