Edge and bulk effects in the Terahertz - photoconductivity of an antidot superlattice

We investigate the Terahertz(THz)-response of a square antidot superlattice by means of photoconductivity measurements using a Fourier-transformspectrometer. We detect, spectrally resolved, the cyclotron resonance and the fundamental magnetoplasmon mode of the periodic superlattice. In the dissipative transport regime both resonances are observed in the photoresponse. In the adiabatic transport regime, at integer filling factor ν = 2, only the cyclotron resonance is observed. From this we infer that different mechanisms contribute to converting the absorption of THz-radiation into photoconductivity in the cyclotron and in the magnetoplasmon resonances, respectively. In the dissipative transport regime, heating of the electrons via resonant absorption of the THz-radiation in the two-dimensional (2D) bulk is the main mechanism of photoconductivity in both resonances. In the case of the cyclotron resonance, and especially in the adiabatic transport regime, we find an additional contribution to photoconductivity which we interprete as being