Anomalous cyclotron resonance linewidth and splitting in heterojunctions displaying the fractional quantum Hall effect

Abstract

We report anomalous structure in the cyclotron resonance linewidth as a function of filling factor for very high mobility GaAs-AlGaAs heterojunctions. These structures are found at or near the filling factors where the fractional quantum Hall effect in these samples occurs. We have also observed a splitting of the CR for ν<1 in a fixed frequency-swept field configuration. We attribute this splitting to the crossing of Landau levels of the two lowest electric subbands. Calculations of this effect on a two-dimensional electron gas have been performed.