CONTROLLABLE SPIN POLARIZATION IN A DMS QUANTUM DOT

The effects of electro-magnetic confining potentials and the s–d exchange interaction between substituted Mn ions and carriers on the spin polarization of carriers in an diluted magnetic semiconductor quantum dot are investigated within the framework of the effective-mass theory. The energy eigenvalues and wavefunctions of a single electron in the presence of an external magnetic field are studied by solving the one particle Schrödinger equation including the conventional Zeeman effect, the s–d exchange interaction and the electric confining potential which describes the dot. The eigenenergy structure for low lying states is strongly dependant on the relative sizes of the s–d exchange interactions and the conventional Zeeman energy splitting. When the spin splitting exceeds the cyclotron energy splitting, the Landau level overlappings occur so that the spin polarization of carriers is induced in low lying energy states. This spin polarization of carriers in the diluted magnetic semiconductor quantum dot can be controlled by changing the electro-magnetic confining potentials.