EFFECT OF THE REDUCTION OF DIMENSIONALITY ON THE EXCHANGE PARAMETERS IN SEMIMAGNETIC SEMICONDUCTORS

We present experimental results showing a variation of the exchange pa rameters between carrier spins and Mn spins as a function of quantum-w ell width in semimagnetic heterostructures. Relative changes of the ex change parameters of about 0.1 are observed by analyzing the Zeeman sp littings of the free-exciton states in epitaxially grown Cd1-xMnxTe/Cd 1-x-yMnxMgyTe quantum wells with no discontinuity of the Mn content at the interfaces. We attribute the well-width dependence of the Zeeman splittings to a k-vector dependence of the exchange parameters.