Cyclotron resonance in the hydrodynamic regime of bi-layer graphene

We calculate the thermo-electric coefficients and extract resonant frequencies for bi-layer graphene in the hydrodynamic regime. In clean systems where interactions are dominated by electron-electron collisions, mild magnetic fields can induce collective cyclotron motion in the charge carrying electrons and holes, with a resonant frequency different from the usual eB/m as a result of electron-hole collisions. We contrast this with single layer graphene, and argue that the hydrodynamic regime in the bilayer case exhibits a broader window where the cyclotron resonance can be accessed by light absorption experiments at room temperature.