  The effects of carrier-impurity correlations due to a Kondo-like spin-spin
interaction in diluted magnetic semiconductors are investigated. These
correlations are not only responsible for a transfer of spins between the
carriers and the impurities, but also produce non-perturbative effects in the
spin dynamics such as renormalization of the precession frequency of the
carrier spins, which can reach values of several percent in CdMnTe quantum
wells. In two-dimensional systems, the precession frequency renormalization for
a single electron spin with defined wave vector shows logarithmic divergences
similar to those also known from the Kondo problem in metals. For smooth
electron distributions, however, the divergences disappear due to the
integrability of the logarithm. A possible dephasing mechanism caused by the
wave-vector dependence of the electron spin precession frequencies is found to
be of minor importance compared to the spin transfer from the carrier to the
impurity system. In the Markov limit of the theory, a quasi-equilibrium
expression for the carrier-impurity correlation energy can be deduced
indicating the formation of strongly correlated carrier-impurity states for
temperatures in the mK range.
