Chiral Anomaly Trapped in Weyl Metals: Nonequilibrium Valley Polarization at Zero Magnetic Field

Kavli Affiliate: Anton R. Akhmerov

| First 5 Authors: Pablo M. Perez-Piskunow, Nicandro Bovenzi, Anton R. Akhmerov, Maxim Breitkreiz,

| Summary:

In Weyl semimetals the application of parallel electric and magnetic fields
leads to valley polarization — an occupation disbalance of valleys of opposite
chirality — a direct consequence of the chiral anomaly. In this work, we
present numerical tools to explore such nonequilibrium effects in spatially
confined three-dimensional systems with a variable disorder potential, giving
exact solutions to leading order in the disorder potential and the applied
electric field. Application to a Weyl-metal slab shows that valley polarization
also occurs without an external magnetic field as an effect of chiral anomaly
"trapping": Spatial confinement produces chiral bulk states, which enable the
valley polarization in a similar way as the chiral states induced by a magnetic
field. Despite its finite-size origin, the valley polarization can persist up
to macroscopic length scales if the disorder potential is sufficiently long
ranged, so that direct inter-valley scattering is suppressed and the relaxation
then goes via the Fermi-arc surface states.

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