Electron-electron interactions induced phases of Weyl semimetals in strong magnetic fields

Weyl nodes are linear band crossings in a Weyl semimetal which can be seen as "magnetic" monopoles of the Berry Curvature in k-space and they always appear in pairs of opposite "charge", or chirality. As more and more of these materials are discovered with different macroscopic properties (dielectric constant, chemical potential...), it is then crucial to understand if there is any interplay between long-range electron-electron interactions and their topological properties.

In a magnetic field, the low-energy electronic dispersion is modified into a set of Landau levels with Landau index n=0,+/-1,+/-2, etc. The n=0 Landau level has a different character than the others. It has a linear dispersion with a slope that is given by the chirality of the node.
In this talk, we will report on a theoretical study of the interplay between the magnetic field, long-range Coulomb interactions and the Berry curvature in Weyl semimetals.
Using the generalized random phase approximation focusing on the n=0 Landau level, we will establish the existence of ordered phases with internode coherence, evaluate their collective modes, and comment on their fingerprints in optical properties.