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 $${{\boldsymbol{{\mathcal{E}}}}}$$ and an applied magnetic field B, to its guiding-center drift, $$({{\boldsymbol{{\mathcal{E}}}}}\times {{{\bf{B}}}})\cdot \sigma$$. The resulting diffusion enhancement yields $$\Delta {R}_{zz}/{R}_{0}=-{\beta }_{g}{({{\boldsymbol{{\mathcal{E}}}}}\times {{{\bf{B}}}})}^{2}$$, with βg set by the quantum metric. Our findings establish a quantum geometric, non-Markovian memory effect in magnetotransport. This study reports gate-tunable giant negative magnetoresistance exceeding − 90% in n-type tellurene thin films, stable up to 35 T at low temperatures and suppressed when the chemical potential moves off the conduction-band Weyl node.