Two-dimensional electron gas coupled to Mn2+ ions:: a magneto-optical study of CdMnTe/CdMgTe MDQWs

We report the results of magneto-optical experiments on two Cd1-xMnxTe/Cd1-yMgyTe modulation-doped single quantum well (QW) structures, with x = 0.005, y = 0.2 and electron sheet concentrations n = 2.9 and 5.65 x 10(11) cm(-2). Experiments have been performed in magnetic fields up to 23 T and at low temperatures down to 75 mK. The results obtained in the range of low magnetic fields (B < 2 T) and at temperatures 1 K < T < 4.2 K are relatively well understood in terms of a standard mean-field approach adapted fur a 2D electronic system coupled to the magnetic environment. Pronounced deviations from the isolated paramagnetic Mn2+ behaviour are observed when lowering the temperature in the low-field limit as well as striking anomalies in the range of high magnetic fields in the vicinities of integer filling factors. (C) 2000 Elsevier Science B.V. All rights reserved.