Optically induced Lifshitz transition in bilayer graphene

It is shown theoretically that the renormalization of the electron energy spectrum of bilayer graphene with a strong high-frequency electromagnetic field (dressing field) results in the Lifshitz transition—the abrupt change in the topology of the Fermi surface near the band edge. This effect substantially depends on the polarization of the field: The linearly polarized dressing field induces the Lifshitz transition from the quadruply connected Fermi surface to the doubly connected one, whereas the circularly polarized field induces the multicritical point where the four different Fermi topologies may coexist. As a consequence, the discussed phenomenon creates a physical basis to control the electronic properties of bilayer graphene with light.

Figure 1

Sketch of the system under consideration: AA-stacked and AB-stacked bilayer graphene subjected to an electromagnetic wave (dressing EM field) propagating perpendicularly to the graphene plane.

Figure 2

The three-dimensional plots of the electron energy spectrum of irradiated AB-stacked bilayer graphene, $\varepsilon$, near the band edge (top) and the corresponding equi-energy maps (bottom) for the linearly polarized dressing field with the photon energy $\hslash \omega =25$ meV and different irradiation intensities, $I$: (a) $I=0$ kW/${\mathrm{cm}}^2$, (b) $I=10$ kW/${\mathrm{cm}}^2$, and (c) $I=45$ kW/${\mathrm{cm}}^2$.

Figure 3

The electronic structure of irradiated AB-stacked bilayer graphene for the circularly polarized dressing field with the photon energy $\hslash \omega =25$ meV: (a) Fermi surface at the monkey-saddle point; (b) Phase diagram of the Fermi surface topology; (c) Density of states spectrum near the monkey-saddle point.