Reversal of the chiral anomaly bulk states with periodically staggered potential

A chiral anomaly Landau level emerges when a Weyl semimetal is subjected to an external magnetic field. Recently, it was demonstrated that similar chiral anomaly bulk states exist within two-dimensional Dirac semimetals if proper boundary conditions are applied. The resulting chiral bulk states disperse linearly with the slope determined by a combination of the boundary condition and chirality of the Dirac cone, i.e., whether it is at K or K' point. In this paper, we show that the slope (the sign of group velocity) near the K and K' points can be reversed under a periodically staggered potential. We first analyze the parameter dependence of this phenomenon with a nearest-neighbor tight-binding model. Then, we give a semianalytical solution for the dispersion of the chiral anomaly bulk states. In the end, we provide a photonic crystal system and prove with full-wave simulations that such a phenomenon can indeed be observed.

Automated summary

A chiral anomaly Landau level arises in the presence of an external magnetic field in a Weyl semimetal. It has been shown recently that similar chiral anomaly bulk states can exist in two-dimensional Dirac semimetals with appropriate boundary conditions. The dispersion of these chiral bulk states depends on both the boundary condition and chirality of the Dirac cone (whether it is at the K or K' point). This paper demonstrates that the slope (sign of group velocity) near the K and K' points can be reversed under a periodically staggered potential. The phenomenon is analyzed using a nearest-neighbor tight-binding model and a semi-analytical solution for the dispersion of the chiral anomaly bulk states is provided. It is further confirmed through full-wave simulations in a photonic crystal system.