Signature of the Chiral Anomaly in Ballistic Magneto-Transport

We compute the magneto-conductance of a short junction made out of a Weyl semi-metal. We show that it displays quantum oscillations at low magnetic field and low temperature, before reaching a universal high-field regime where it increases linearly with the field. Besides identifying a new characterization of the physics of materials with Weyl singularities in their energy spectrum, this ballistic regime corresponds to the simplest setup to study and understand the manifestation of the so-called chiral anomaly of massless relativistic particles in condensed matter. At low fields the algebraic in field magneto-conductance incorporates contributions besides the anomalous chiral current while the linear conductance at higher fields constitutes an unambiguous signature of the chiral anomaly in a Weyl conductor. Finally, we study the dependence of the ballistic magneto-conductance on the chemical potential, and discuss the cross-over towards the diffusive regime when elastic scattering is present.