Time-resolved magnetophotoluminescence studies of magnetic polaron dynamics in type-II quantum dots

TL;DR

This study compares magnetic polaron dynamics in two types of quantum dot systems using photoluminescence spectroscopy, revealing distinct behaviors based on the Mn ion location, with implications for understanding magnetic interactions in quantum dots.

Contribution

It provides the first detailed comparison of magnetic polaron properties in two related type-II quantum dot systems with different Mn ion placements.

Findings

Magnetic polaron formation energies were measured from temporal red-shift.

In ZnTe/(Zn,Mn)Se, MP behavior decreases with T and B.

In (Zn,Mn)Te/ZnSe, MP shows weak dependence on T and B.

Abstract

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 non-magnetic 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 non-magnetic ZnSe matrix. The magnetic polaron formation energies in both systems were measured from the temporal red-shift 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 decreasing with increasing temperature T and increasing magnetic field B. In contrast, in the (Zn,Mn)Te/ZnSe system has unconventional dependence on temperature T and magnetic field B; 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.