  Time-resolved optically detected magnetic resonance (ODMR) is a valuable
technique to study the local deformation of the crystal lattice around magnetic
ion as well as the ion spin relaxation time. Here we utilize selective
Mn-doping to additionally enhance the inherent locality of the ODMR technique.
We present the time-resolved ODMR studies of single {(Cd,Mg)Te/(Cd,Mn)Te}
quantum wells (QWs) with manganese ions located at different positions along
the growth axis -- in the center or on the sides of the quantum well. We
observe that spin-lattice relaxation of Mn$^{2+}$ significantly depends on the
ion-carrier wavefunction overlap at low-magnetic fields. Interestingly, the
effect is clearly observed in spite of very low carrier density, which suggests
the potential for control of the Mn$^{2+}$ ion relaxation rate by means of the
electric field in future experiments.
