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Advances in Condensed Matter Physics
Volume 2009, Article ID 561201, 7 pages
http://dx.doi.org/10.1155/2009/561201
Research Article

Spin Polarization and Exchange Interaction in a Diluted Magnetic Qunautm Dot

1Government Arts College, Melur, Madurai-625 106, India
2Arul Anandar College, Karumathur, Madurai-625 514, India

Received 15 October 2008; Revised 20 February 2009; Accepted 1 April 2009

Academic Editor: Joseph Poon

Copyright © 2009 A. John Peter and K. Lily Mary Eucharista. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The spin interaction energy of different ions with and without an itinerant electron is evaluated for different dot radii. Magnetization is calculated for various concentrations of ions with different dot sizes. Spin polaronic shifts are estimated using a mean field theory. The lowest binding energies of electrons in a quantum dot are also calculated. Results are obtained for structures as a function of the dot radius variationally. It is found that (i) more number of spins enhance the spin polaronic effect and it varies linearly with the concentration, (ii) spin polarization of ions increases with the concentration for any dot radii, (iii) the magnetization of Mn subsystem increases with the concentration of 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.