Ohm’s law is a fundamental paradigm in the electrical transport of metals¹. Any transport signatures violating Ohm’s law would give an indisputable fingerprint for a novel metallic state. Here, we uncover the breakdown of Ohm’s law owing to a topological structure of the chiral anomaly in the Weyl metal phase. We observe nonlinear I–V characteristics in Bi_0.96Sb_0.04 single crystals in the diffusive limit, which occurs only for a magnetic-field-aligned electric field (E∥B). The Boltzmann transport theory with the charge pumping effect reveals the topological-in-origin nonlinear conductivity, and it leads to a universal scaling function of the longitudinal magnetoconductivity, which completely describes our experimental results. As a hallmark of Weyl metals, the nonlinear conductivity provides a venue for nonlinear electronics, optical applications, and the development of a topological Fermi-liquid theory beyond the Landau Fermi-liquid theory.

欧姆定律是金属电传输¹的基本范式。任何违反欧姆定律的运输签名都会给新型金属态带来无可辩驳的指纹。在这里，我们发现由于Weyl金属相中手性异常的拓扑结构而导致的欧姆定律的分解。我们在扩散极限中观察到Bi _0.96 Sb _0.04单晶中的非线性I – V特性，这种特性仅在磁场对准的电场中发生（E∥B）。具有电荷泵效应的玻耳兹曼输运理论揭示了起源于拓扑的非线性电导率，并导致了纵向磁导率的通用缩放函数，从而完全描述了我们的实验结果。作为Weyl金属的标志，非线性电导率为非线性电子学，光学应用以及超越Landau费米液体理论的拓扑费米液体理论的发展提供了场所。