Spin polarization and exchange interaction in a diluted magnetic qunautm dot

Abstract

The spin interaction energy of different Mn 2+ ions with and without an itinerant electron is evaluated for different dot radii. Magnetization is calculated for various concentrations of Mn 2+ ions with different dot sizes. Spin polaronic shifts are estimated using a mean field theory. The lowest binding energies of electrons in a Cd 1-x Mn x Te quantum dot are also calculated. Results are obtained for C d 1- x in M n x in Te/C d 1- x out M n x out Te structures as a function of the dot radius variationally. It is found that (i) more number of Mn 2+ spins enhance the spin polaronic effect and it varies linearly with the concentration, (ii) spin polarization of Mn 2+ ions increases with the concentration for any dot radii, (iii) the magnetization of Mn subsystem increases with the concentration of Mn 2+ ions and this feature is predominant for smaller dots, and (iv) variation of increase in ionization energy is sharper for smaller dots with increase in concentration. These results are discussed with the available data in literature. Copyright © 2009 A. J. Peter and K. L. M. Eucharista.