Direct Measurement of the g-Factor of Composite Fermions
Abstract
The activation gap \Delta of the fractional quantum Hall states at constant fillings \nu =2/3 and 2/5 has been measured as a function of the perpendicular magnetic field B. A linear dependence of \Delta on B is observed while approaching the spin polarization transition. This feature allows a direct measurement of the g-factor of composite fermions which appears to be heavily renormalized by interactions and strongly sensitive to the electronic filling factor.