CPM Seminar

Combining magnetic and semiconductor properties in
nanoscale engineered diluted magnetic semiconductors

Jacek Kossut

Institute of Physics
Polish Academy of Sciences

Diluted magnetic semiconductors (DMS) are a class of semiconductor materials incorporating magnetic ions. I will describe our work combining magnetic and semiconductor properties in nanoscale engineered diluted magnetic semiconductors. We will start with self-assembled quantum dots made of a diluted magnetic semiconductor CdMnTe embedded in ZnCdTe matrix. Results of microluminescence measurements in the presence of an external magnetic field will be discussed in terms of two model approaches: mean field approach and magnetic molecule approach. We shall attempt to reproduce the magnitude of the observed giant Zeeman splitting of excitonic signatures and the line width behavior as functions of the field. Surprisingly, the spin splitting at saturation seems to acquire several nearly discrete values. In a second part I will describe an alternative method of controlling optical properties of DMS in hybrid structures of diluted magnetic semiconductors and ferromagnetic micromagnets. The structures consist of a thin quantum well made of diluted magnetic semiconductor (DMS) CdMnTe buried shallowly under the surface and small micromagnets deposited on top of the surface. Optical studies of the luminescence excited in such structures making use of an extreme sensitivity of DMS to an external magnetic field via the giant Zeeman splitting do show that there is a possibility to localize spatially the excitons with use of the fringe fields originated from the presence of the micromagnets. We shall show several experiments that provide an evidence of such localization.