Metal-insulator transition in a semimagnetic parabolic quantum well

Calculation of binding energy of a hydrogenic donor in a parabolic quantum well of Cd1-zinMnxinTe/Cd1-xoutMnxoutTe superlattice system is obtained. A variational procedure within the effective mass approximation is employed in the presence of magnetic field. We assume that the impurity ion is located at the center of the well. Within the one-electron approximation, it is observed that the occurrence of Mott transition is seen when the binding energy of a donor vanishes. The effects of Anderson localization and exchange and correlation in the Hubbard model are included in our model. For a given value of the magnetic field, the binding energy is found to be smaller than the zero-field case. The results show that the ionization energy (i) decreases as well width increases for a given magnetic field, (ii) the critical concentration at which the metal-insulator transition occurs is enhanced in the external magnetic field and (iii) spin polaronic shifts not only decrease in a magnetic field but also with the well width. All the calculations have been carried out with finite barriers and the results are compared with available data in the literature. (c) 2006 Elsevier B.V. All rights reserved.