The chiral anomaly is a quantum anomaly in the massless quantum electrodynamics (QED). Upon quantization
of the classical QED, the conservation of the chiral current is violated by an anomalous contribution
that is nonzero in the presence of non-orthogonal electric and magnetic fields. In their
seminal work, Nielsen and Ninomiya
demonstrate that the chiral anomaly can be observed in semiconductors where the conduction bands and the valence
bands meet at pointlike degeneracies. These materials are known as the Weyl semimetals, because the
low-energy excitations near the gapless points are described by the Weyl equations. In Weyl semimetals,
non-orthogonal electric and magnetic fields cause electrons to evolve along counter-propagating chiral Landau levels,
resulting in excess chiral charge.
In this work, we investigate a different type of chiral anomaly in Weyl semimetals arising from strain-induced
pseudo-electromagnetic fields. Twisting a Weyl semimetal nanowire induces a pseudo-magnetic field; whereas
sending a mechanical wave (e.g. sound wave) through a Weyl semimetal generates an oscillating pseudo-electric
field. We show that certain combinations of pseudo and conventional electromagnetic fields give rise to a dynamic charge re-distribution between the bulk and the surface of the
Weyl semimetal, which violates charge conservation in the bulk. We further discuss experimentally observable consequences
in Dirac semimetals Cd3As2 and Na3Bi.