Spin Polarization and Exchange Interaction in a Diluted Magnetic Qunautm Dot

Abstract

The spin interaction energy of differentMn2+ions with and without an itinerant electron is evaluated for different dot radii. Magnetization is calculated for various concentrations ofMn2+ions with different dot sizes. Spin polaronic shifts are estimated using a mean field theory. The lowest binding energies of electrons in aCd1-xMnxTequantum dot are also calculated. Results are obtained forCd1−xinMnxinTe/Cd1−xoutMnxoutTestructures as a function of the dot radius variationally. It is found that (i) more number ofMn2+spins enhance the spin polaronic effect and it varies linearly with the concentration, (ii) spin polarization ofMn2+ions increases with the concentration for any dot radii, (iii) the magnetization of Mn subsystem increases with the concentration ofMn2+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.

Increased static dielectric constant in ZnMnO and ZnCoO thin films with bound magnetic polarons

“…Due to the s-d exchange interaction between the spin of singly charged oxygen vacancy + V o and the spins of the 3d transition metal ions in the sphere with Bohr radius r B , the spins of the 3d transition metal ions the align in same direction and sum up to the collective spin of the BMP. For example, spontaneous magnetization due to collective spins of BMPs in CdTe with substitutional Mn ions was reported by Peter and Eucharista 12 . From magnetic n-CdS 13,14 and n-CdSe 15,16 there is abundant evidence that the electron localized at the impurity in the BMP center can induce sizable magnetization in its vicinity, often having magnetic moments exceeding 25 μ B…”