  Spatially indirect Type-II band alignment in magnetically-doped quantum dot
(QD) structures provides unexplored opportunities to control the magnetic
interaction between carrier wavefunction in the QD and magnetic impurities.
Unlike the extensively studied, spatially direct, QDs with Type-I band
alignment where both electrons and holes are confined in the QD, in ZnTe QDs
embedded in a (Zn,Mn)Se matrix only the holes are confined in the QDs.
Photoexcitation with photon energy 3.06 eV (2.54 eV) generates electron-hole
pairs predominantly in the (Zn,Mn)Se matrix (ZnTe QDs). The photoluminescence
(PL) at 7 K in the presence of an external magnetic field exhibits an up to
three-fold increase in the saturation red shift with the 2.54 eV excitation
compared to the shift observed with 3.06 eV excitation. This unexpected result
is attributed to multiple hole occupancy of the QD and the resulting increased
penetration of the hole wavefunction tail further into the (Zn,Mn)Se matrix.
The proposed model is supported by microscopic calculations which accurately
include the role of hole-hole Coulomb interactions as well as the hole-Mn spin
exchange interactions.
