Large Filling-Factor-Dependent Spin Splitting in Magnetooptic Kerr Effect in GaAs/AlGaAs Multiple Quantum Wells

Magnetooptic Kerr effect in GaAs/Al$\text{}_{0.312}$Ga$\text{}_{0.688}$As multiple quantum wells was investigated in the integer quantum Hall regime. The measurements have been performed in magnetic fields up to 14.5 T, at the temperature of 1.8 K. Experimental data indicate the discontinuous behavior of the magnetooptic Kerr effect spectrum as a function of the filling factor. For odd filling factor values ν=3 and 5 we observe the large spin splitting. The effects cannot be explained in the one-particle model.