Dirac magnons in honeycomb nanostructures

Magnon eigenmodes of an artificial structure consisting of cylindrical nanometric particles arranged in a honeycomb array are theoretically investigated, in zero applied field. The dispersion curves of the fundamental mode are calculated for two principal directions of the first Brillouin zone. A Dirac-like behavior, consisting of linear band crossing and zero-width gap, is found for moderate interdot separation. A tight-binding model fits the calculated behavior; the corresponding Dirac velocity has been obtained.