FAR-INFRARED RESPONSE OF LATERAL SUPERLATTICES IN HIGH MAGNETIC-FIELDS

We study the high-frequency response of lateral superlattices in high magnetic fields in the transition regime from a two-dimensional electron gas to isolated electron dots. For largely different samples we find that the far-infrared-active modes of electron dots and antidots develop out of the cyclotron resonance rather than out of the magnetoplasmon. The transition from the (single) cyclotron resonance to the two resonances that make up the antidot spectrum takes place quite abruptly when the potential maxima start to exceed the Fermi energy. A classical, single-particle model of ballistically moving electrons is presented that can account for the experimental observations. In view of these findings the role of many-particle contributions in lateral superlattices in high magnetic fields is discussed.