Chiral magnetic effect in a topological Weyl semimetal

Carlo Beenakker, Instituut-Lorentz, Leiden University

The conduction electrons in a Weyl semimetal have an unusual velocity distribution in the Brillouin zone. The conical band structure (Weyl cone) has a chirality that generates a net current at the Fermi level in the presence of a magnetic field. The Weyl cones come in pairs of opposite chirality, so that the total current vanishes in equilibrium, but a nonzero current parallel to the field remains if the cones are offset in energy. This is the chiral magnetic effect from particle physics. Here we show that in condensed matter this effect is strongly modified by the topologically protected surface states in a Weyl semimetal, the socalled "surface Fermi arcs". These offer the possibility to observe the chiral magnetic effect without Landau levels.