Light scattering by magnetorotons of collective excitations in the fractional quantum Hall regime

Magnetorotons in the dispersion curves of collective gap excitation modes of fractional quantum Hall liquids are measured by resonant inelastic light scattering. Two deep magnetoroton minima are observed at View the MathML source, while a single deep minimum is resolved at View the MathML source. The results support Chern–Simons and composite fermion calculations that predict multiple roton minima for states with View the MathML source.