Dynamics of exciton magnetic polarons in Cd1-xMnxTe/Cd1-x-yMnxMgyTe quantum wells

We study the influence of quantum confinement and spin-lattice relaxation on the dynamics of exciton magnetic polaron formation in specially designed semimagnetic quantum wells. Using low temperature time-resolved photoluminescence with variable pulse separation we show that a decrease of the well width does not only enhance the polaron energy but also shortens its formation time. Comparison with numerical calculations reveal that the latter can be associated with smaller changes of the excitonic wave function during polaron formation. In addition, by measuring the polaron formation time as a function of pulse separation we show that spin-lattice coupling influences the polaron dynamics indirectly rather than directly by transferring the polaron induced energy gain of the spin-system to the lattice.