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Résumé |
We consider dressing of excitonic properties by strongly correlated electrons in
gate-controlled twisted homo-bilayer heterostructures, as analyzed in recent experiments.
The combined effect of the moiré potential and the Coulomb interaction supports the
formation of different strongly correlated phases which depend on the filling, including
charge-ordered metals or incompressible insulators at integer occupation. The coupling
between excitons and electrons results in a splitting of the excitonic resonance into an
attractive and a repulsive polaron peak. Analysing the properties of such exciton-polarons
across the different phases of the system, we reveal a discontinuous evolution of the
spectrum with the formation of a double-peak structure in the repulsive polaron branch. The
double-peak structure emerges for non-integer fillings and it is controlled by the energy
separation between the quasiparticle states close to the Fermi level and the high-energy
excitations. Our results demonstrate that exciton-polarons carry a clear hallmark of the
electronic correlations and, thus, provide a direct signature of the formation of
correlation-driven insulators in gate-controlled heterostructures.
[1] "Strongly correlated exciton-polarons in twisted homobilayer heterostructures" G.Mazza and A.Amaricci, Physical Review B letter, 106, L241104 (2022)
[2] "Strongly correlated electrons and hybrid excitons in a moiré heterostructure", Y.Shimanzaki, Nature (London)
580, 472 (2020). |
