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

Abstract
The authors report anomalous structure in the cyclotron resonance linewidth as a function of filling factor for very high-mobility GaAs-AlGaAs heterojunctions, using far infrared transmission at T=1.4K. These structures are found at or near the filling factors where the fractional quantum Hall effect (FQHE) in these samples occurs ( nu =4/3, 5/3 and 7/3). The cyclotron effective mass shows no anomalies at those filling factors. An attempt has been made to explain this in the context of the theories on the origin of the FQHE.