FRACTIONAL QUANTUM HALL EFFECT MEASUREMENTS AT ZERO G FACTOR

Fractional quantum Hall effect energy gaps have been measured as a function of Zeeman energy. The gap at ν = 1/3 decreases as the g factor is reduced by hydrostatic pressure. This behavior is similar to that at ν = 1 and shows that the excitations are spinlike. At small Zeeman energy, the excitation is consistent with the reversal of 3 spins and may be interpreted as a small composite Skyrmion. At 20 kbar, where g has changed sign, the 1/3 gap appears to increase again.