Fractional quantum Hall effect energy gaps have been measured in GaAs/GaAlAs heterojunctions as a function of Zeeman energy, which is varied by applying hydrostatic pressure up to 20 kbar. The gap at v=1/3 decreases with pressure until the g-factor changes sign when it again increases. The behavior is similar to that seen at v=1 and shows that excitations from the 1/3 ground state can be spin-like in character. At small Zeeman energy, the excitation appears to consist of 3 spins and may be interpreted as a small composite skyrmion.
@article{arxiv.cond-mat/9706157,
title = {Fractional Quantum Hall Effect Measurements at Zero g-Factor},
author = {D. R. Leadley and R. J. Nicholas and D. K. Maude and A. N. Utjuzh and J. C. Portal and J. J. Harris and C. T. Foxon},
journal= {arXiv preprint arXiv:cond-mat/9706157},
year = {2009}
}