Rotons of composite fermions: Comparison between theory and experiment

Department of Physics, 104 Davey Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802(February 1, 2008)A major obstacle toward a quantitative verification, by comparison to experiment, of the theory ofthe excitations of the fractional quantum Hall effect has been the lack of a proper understandingof disorder. We circumvent this problem by studying the neutral magneto-roton excitations, whoseenergy is expected to be largely insensitive to disorder. The calculated energies of the roton at1/3, 2/5 and 3/7 fillings of the lowest Landau level are in good agreement with those measuredexperimentally.PACS numbers:71.10.Pm,73.40.Hm