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

Abstract

Magnetooptic Kerr effect in GaAs/Al0.312 Ga0.688 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 v = 3 and 5 we observe the large spin splitting. The effects cannot be explained in the one-particle model.PACS numbers: 78.20. Ls, 73.20.Dx, 78.66.Fd Interband magnetooptical spectroscopy in strong magnetic fields is a sensitive method in studies of two-dimensional electron gas (2DΕG) [1][2][3][4][5]. It allows us to study the correlations between the optical properties of 2DΕG and the integer and fractional quantum Hall effects (ΙQHE and FQHE). Many experimental and theoretical papers are devoted to quantum Hall state with filling factor v = 1, when all electrons occupy the spin-split lowest Landau level [6][7][8][9]. It was established that the v = 1 state is governed predominantly by the ferromagnetic many-body exchange interaction (the skyrmions). Our report concerns the magnetooptical properties of the 2DΕG at higher filling factors v > 1.In most cases the method of photoluminescence (PL), photoluminescence excitation (PLE), and the method of reflectance were used. The PL and PLE depend on complicated relaxation effects that take place before the electrons relax to the lowest energy state. Therefore, some people prefer to use the magnetoabsorption [2,6,8].