Relativistic mechanism of chiral magnetic current in Weyl semimetals with tilted dispersion

Abstract

The chiral magnetic effect is a one of the exotic bulk transport properties of the Weyl semimetals. Because of the Nielsen–Ninomiya ‘no-go theorem’, the total chiral magnetic current is absent in the equilibrium state. One of the mechanisms for generating this current is the chiral anomaly. This phenomenon is the anomalous nonconservation of chiral charge for massless relativistic particles. It can be realized by parallel magnetic and electric fields (∼), and it leads to such new transport phenomenon as the negative longitudinal magnetoresistance. Using a simple theory (we consider both a linearized and lattice model), we have shown, that in Weyl metals with tilted dispersion another mechanism of the chiral magnetic current is possible. It is not associated with the chiral anomaly. The new transport mechanism is based on the relativistic effect of electric field on Landau levels. This effect is that an electric field changes the distance between the Landau levels, and also changes the effective velocity along magnetic field. At the presence of a tilt in the spectrum, this velocity renormalization is different for different Weyl points. This leads to a non-zero resulting drift velocity. As a consequence, an electrical current arises along the magnetic field. The induced by this mechanism the electric current is proportional to the pseudoscalar product of the fields () and directed along the magnetic field, that differs it from the Hall current (∼). At the same time, the conductivity corresponding to this transport mechanism does not depend on the scattering time like the Hall conductivity. Thus, we have proposed a new anomalous transport mechanism in the Weyl semimetal, which is not associated with the chiral anomaly.