Consistent chiral kinetic theory and hydrodynamics in Weyl semimetals

Synopsis

Weyl semimetals, whose low-energy quasiparticle excitations are described by the Weyl equation, became an active and vibrant area of research in condensed matter physics-archive. Their unusual properties can be described by various methods ranging from the quantum field theory to semi-classical approaches. The latter include the chiral kinetic theory and hydrodynamics. It is argued that the correct definition of the electric current in the chiral kinetic theory for Weyl semimetals should necessarily include the topological Chern-Simons contributions. The latter make the theory consistent with the local conservation of the electric charge in electromagnetic and strain-induced pseudoelectromagnetic fields. By making use of such a kinetic theory, electron collective excitations in constant magnetic and pseudomagnetic fields are investigated. Among the most interesting results are the transformation of the chiral magnetic wave into the chiral magnetic plasmon due to the effects of dynamical electromagnetism and the existence of pseudomagnetic helicons in strained Weyl semimetals. The latter are similar to usual helicons in metals but can exist even without external magnetic fields allowed by a strain-induced background pseudomagnetic field. Based on the consistent chiral kinetic theory, a consistent hydrodynamics for Weyl electrons is formulated and a few applications are discussed.