Magnetoplasmons in a Tunable Periodically Modulated Magnetic Field

We report the first infrared optical measurements of a two dimensional electron gas (2DEG) in a periodically modulated magnetic field. The 2DEG is produced using epitaxial regrowth on a corrugated surface, so that the component of an externally applied magnetic field perpendicular to the 2DEG is spatially modulated. Two active modes are observed, with intensities and frequencies which depend on the amplitude of the field modulation as well as the total external magnetic field. These modes arise from field modulation-induced coupling between the 2DEG magnetoplasmons. Calculations of the magnetoplasmon band structure in a modulated field are in excellent agreement with the experimental data.