Nonreciprocal propagation and localization of plasmons by a magnetic field in finite semiconductorn-i-p-isuperlattices

We consider the effects of an external magnetic field on plasmons propagating in finite n-i-p-i (n-doped material--insulator--p-doped material--insulator) superlattices. The magnetic field is applied parallel to the interfaces and we consider propagation perpendicular to the applied field. We find that the magnetic field can have two effects: (1) the dispersion relations can become nonreciprocal, or (2) the excitations can become (nonreciprocally) localized. The particular effect depends critically upon the number of layers; for a structure composed of an unequal number of n- and p-doped layers, the modes can be strongly localized, while in a structure composed of an equal number of n- and p-doped layers the dispersion curves become nonreciprocal.