Collective modes in a Dirac insulator with short range interactions
Collective modes in a Dirac insulator with short range interactions
We study a Haldane model with nearest neighbor interactions. We find one-dimensional-like collective modes arising due to the interplay of pseudospin and valley degrees of freedom. In the large-band-gap or moderate interaction limit, these excitations are low energy modes lying in the band gap. The dispersion relations are qualitatively different …