We used continuous wave photoluminescence (cw-PL) and time-resolved photoluminescence (TR-PL) spectroscopy to compare the properties of magnetic polarons (MP) in two related spatially indirect II-VI epitaxially grown quantum dot systems. In the ZnTe/(Zn,Mn)Se system the holes are confined in the nonmagnetic ZnTe quantum dots (QDs), and the electrons reside in the magnetic (Zn,Mn)Se matrix. On the other hand, in the (Zn,Mn)Te/ZnSe system, the holes are confined in the magnetic (Zn,Mn)Te QDs, while the electrons remain in the surrounding nonmagnetic ZnSe matrix. The magnetic polaron formation energies EMP in both systems were measured from the temporal redshift of the band-edge emission. The magnetic polaron exhibits distinct characteristics depending on the location of the Mn ions. In the ZnTe/(Zn,Mn)Se system the magnetic polaron shows conventional behavior with EMP decreasing with increasing temperature T and increasing magnetic field B. In contrast, EMP in the (Zn,Mn)Te/ZnSe system has unconventional dependence on temperature T and magnetic field B; EMP is weakly dependent on T as well as on B. We discuss a possible origin for such a striking difference in the MP properties in two closely related QD systems.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 24 Jul 2015|