Gate-tunable giant negative magnetoresistance in tellurene driven by quantum geometry

Negative magnetoresistance in conventional two-dimensional electron gases is a well known phenomenon, but its origin in complex and topological materials endowed with nontrivial quantum geometry remains elusive. Here, we report a giant negative magnetoresistance reaching  -90% of the zero-field resistance, R₀, in n-type tellurene films. The effect persists up to 35 T at cryogenic temperatures and is suppressed when the chemical potential moves away from the conduction-band Weyl node, suggesting a quantum geometric origin. We propose two mechanisms: quantum geometric enhancement of diffusion and a magnetoelectric spin interaction that locks the spin of a cyclotron-moving Weyl fermion, in the presence of an intrinsic inversion-breaking polar field $E$ and an applied magnetic field B, to its guiding-center drift, $\left(E\times B\right)\cdot \sigma$ . The resulting diffusion enhancement yields $\Delta R_{zz}/R_0=-{\beta }_g{\left(E\times B\right)}^2$ , with β_g set by the quantum metric. Our findings establish a quantum geometric, non-Markovian memory effect in magnetotransport.