Signatures of spin in the n=1/3 Fractional Quantum Hall Effect
  The activation gap Delta of the fractional quantum Hall state at constant filling n =1/3 is measured in wide range of perpendicular magnetic field B. Despite the full spin polarization of the incompressible ground state, we observe a sharp crossover between a low-field linear dependence of Delta on B associated to spin texture excitations and a Coulomb-like behavior at large B.   From the global gap-reduction we get information about the mobility edges in the fractional quantum Hall regime. 
A. F. Dethlefsen, E. Mariani, H.-P. Tranitz, W. Wegscheider, R. J.   Haug