Resistively detected EPR of Mn2+ ions coupled to the 2DEG in the quantum Hall regime

An investigation of resistively detected electron paramagnetic resonance (EPR) of Mn2+ ions imbedded in CdMnTe modulation-doped quantum well structure reveals the strong influence of the 2D-free carriers on the resonance position (Knight shift). The EPR experiments have been performed at low fields and for a ν=3 quantum Hall state. The observed Knight shift at ν=3 is huge and cannot be explained by standard models (mean field approach) of mutual interaction between spins of band electrons and magnetic moments in diluted magnetic semiconductors.