Axial anomaly and longitudinal magnetoresistance of a generic three dimensional metal

Understand

We show that the emergence of the axial anomaly is a universal phenomenon for a generic three dimensional metal in the presence of parallel electric ($E$) and magnetic ($B$) fields.

• In contrast to the expectations of the classical theory of magnetotransport, this intrinsically quantum mechanical phenomenon gives rise to the longitudinal magnetoresistance for any three dimensional metal.
• However, the emergence of the axial anomaly does not guarantee the existence of negative longitudinal magnetoresistance.
• We show this through an explicit calculation of the longitudinal magnetoconductivity in the quantum limit using the Boltzmann equation, for both short-range neutral and long-range ionic impurity scattering processes.