Light scattering by low lying quasiparticle excitations in the fractional quantum Hall regime

Low lying excitations of electron liquids in the fractional quantum Hall (FQH) regime are studied by resonant inelastic light scattering methods. We present here results from charge and spin excitations of FQH states in the lowest spin-split Landau levels that are of current interest. In the range of filling factors 2/5 greater than or equal to nu greater than or equal to 1/3, we find evidence that low-energy quasiparticle excitations can be interpreted with spin-split composite fermion quasi-Landau levels. At FQH states around nu = 3/2, we find well-defined excitations at 4 and 8 that are consistent with a spin-unpolarized population of quasi-Landau levels. (C) 2003 Published by Elsevier B.V.