AQP -seminaari: Consistent chiral kinetic theory in Weyl semimetals

Aalto Quantum Physics -seminaari (Nanotalo). Puhuja: Dr. Pavlo Sukhachov (Nordita, KTH Royal Institute of Technology and Stockholm Unversity)

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. Their unusual properties can be described by various methods ranging from the quantum field-theoretical to semiclassical approaches such as the chiral kinetic theory. 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 this kinetic theory, electron collective excitations in constant magnetic and pseudomagnetic fields are investigated. Among the most interesting results are (i) the transformation of the chiral magnetic wave into the chiral magnetic plasmon due to the effects of dynamical electromagnetism and (ii) 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.