  The dynamics of spin-lattice relaxation of the Mn-ions in (Zn,Mn)Se-based
diluted-magnetic-semiconductor quantum wells is studied by time-resolved
photoluminescence. The spin-lattice relaxation time varies by five orders of
magnitude from 10-3 down to 10-8 s, when the Mn content increases from 0.4 up
to 11%. Free carriers play an important role in this dynamics. Hot carriers
with excess kinetic energy contribute to heating of the Mn system, while
cooling of the Mn system occurs in the presence of cold background carriers
provided by modulation doping. In a Zn0.89Mn0.11Se quantum well structure,
where the spin-lattice relaxation process is considerably shorter than the
characteristic lifetime of nonequilibrium phonons, also the phonon dynamics and
its contribution to heating of the Mn system are investigated.
