title: Observation of multiple magnetorotons in the fractional quantum Hall effect.
abstract: Magnetorotons in the dispersions of collective gap excitation modes of fractional quantum Hall liquids are measured in resonant inelastic light scattering experiments. Two deep magnetoroton minima are observed at nu = 2/5, while a single deep minimum is resolved at nu = 1/3. The observations are the first evidence of multiple roton minima in gap excitations of the quantum liquids. The results support Chern-Simons and composite fermion calculations that predict multiple roton minima for states with nu>1/3.
authors: Bell Labs, Lucent Technologies, Murrray Hill, NJ 07974, USA.
authors: M
authors: M
authors: Kang
authors: A
authors: A
authors: Pinczuk
authors: B S
authors: BS
authors: Dennis
authors: L N
authors: LN
authors: Pfeiffer
authors: K W
authors: KW
authors: West