title: Optical investigation of spin-wave excitations in fractional quantum hall states and of interaction between composite fermions
abstract: We demonstrate that the temperature dependence of the electron spin polarization for the fractional states nu = 1/3 and nu = 2/3 displays activated behavior. This study enables the first measurement of the fractional quantum Hall spin-flip gaps. They are found to be systematically larger in comparison with the gaps simultaneously measured in transport. For nu = 1/3 and nu = 1/2, these spin-flip gaps allow the determination of the composite fermion interaction energy. This energy is investigated as a function of the finite width of the 2D channel.
authors.affiliation: Max-Planck-Institut fur Festkorperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany and Institute of Solid State Physics, RAS, Chernogolovka, 142432 Russia.
authors.initials: IV
authors.lastname: Kukushkin
authors.initials: JH
authors.lastname: Smet
authors.lastname: von Klitzing K
authors.initials: K
authors.lastname: Eberl