High-frequency irradiation used for enabling exciton formation and superfluidity in kagome double layers

We investigate the effects due to irradiation on the kagome lattice materials employing the high- frequency Floquet-Magnus perturbation to open a gap between the valence and conduction bands near the Fermi level. We demonstrate that circularly polarized light opens a band gap near the Dirac points unlike linearly olarized light, and enables control over the exciton binding energies and the Kosterlitz–Thouless phase transition. We compare the exciton binding energy and exciton energy in a monolayer with those in a double layer consisting of electrons in one layer and holes in a parallel layer, separated by an insulator. Our results demonstrate that circular irradiation can enable a transition from a semiconducting to an excitonic insulating phase as well as supports the emergence of dipolar exciton superfluidity and Bose-Einstein condensation in double-layer kagome lattices. Additionally, the results establish that superfluid density, collective excitations, and critical temperature can be tuned through exciton density, interlayer separation, and light parameters.