ZnTe/CdSe type-II core/shell spherical quantum dot under an external electric field

International audienceWe have investigated in the framework of the envelope function approximation and taking into account the dependence of the electron effective mass on radius the energy of an electron inside a ZnTe/CdSe core/shell spherical quantum dot. In order to make the problem more realistic, we describe the conduction band-edge alignment between core and shell materials by a finite height barrier. By applying the Ritz variational principle the effect of the electric field on the electronic states was also examined. Our numerical results show the opportunity to control the energy states position of the charge carriers inside our core/shell nanostructures by controlling the size (core radius, shell thickness) of the nanostructure and the strength of the external electric field

Magnetic properties in ferroelectric superlattices described by a transverse spin-1/2 Ising model

The temperature dependence of the longitudinal magnetization as well as the longitudinal susceptibility of a ferroelectric superlattice described by a transverse spin-1/2 Ising model are studied using the effective field theory with a probability distribution technique that accounts for the self-spin correlations. When the slab thicknesses are larger, the temperature dependence of the magnetization shows a steplike structure. The susceptibility becomes infinite at the critical temperature T-c and shows a finite peak corresponding to the rapid decrease in the magnetization near the bulk critical temperature of slab B. The height of the finite peak decreases with the decrease in the slab thicknesses. When they become so thin that the magnetization profiles are predominantly controlled by the interface, the finite peak in the susceptibility as well as the steps in magnetization disappear. (C) 2002 Elsevier Science B.V. All rights reserved