Quantized electrochemical transport in Weyl semimetals

We show that under the effect of an external electric field and a gradient of chemical potential, a topological electric current can be induced in Weyl semimetals without inversion and mirror symmetries. We derive analytic expressions for the nonlinear conductivity tensor and show that it is nearly quantized for small tilting when the Fermi levels are close to the Weyl nodes. When the Van Hove point is much larger than the largest Fermi level, the band structure is described by two linearly dispersing Weyl fermions with opposite chiralities. In this case, the electrochemical response is fully quantized in terms of fundamental constants and the scattering time, and it can be used to measure directly the topological charge of Weyl points. We show that the electrochemical chiral current may be derived from an electromagnetic action similar to axion electrodynamics, where the position-dependent chiral Fermi level plays the role of the axion field. This posits our results as a direct consequence of the chiral anomaly.

Automated summary

The study demonstrates that a topological electric current can be induced in Weyl semimetals under an external electric field and chemical potential gradient, providing nearly quantized expressions for nonlinear conductivity tensor. When Fermi levels are close to Weyl nodes, the electrochemical response can be quantized in terms of fundamental constants and scattering time under small tilting. This electrochemical chiral current may be derived from an electromagnetic action similar to axion electrodynamics, indicating a direct consequence of the chiral anomaly.