Unpaired Weyl nodes from Long-Ranged Interactions: Fate of Quantum Anomalies

Understand

We study the effect of long-ranged interactions on Weyl semimetals.

• Such interactions can give rise to unpaired Weyl nodes, which we demonstrate by explicitly constructing a system with just a single node - a situation that is fundamentally forbidden by fermion doubling in non-interacting band structures.
• Adding a magnetic field, we investigate the fate of the chiral anomaly.
• Remarkably, as long as a system exhibits a single Weyl node in the absence of magnetic fields, arbitrarily weak fields qualitatively restore the lowest Landau level structure of a non-interacting Weyl semimetal.