Electronic states of magnetic quantum dots

We study quantum states of electrons in magnetically doped quantum dots as a function of exchange coupling between electron and impurity spins, the strength of Coulomb interaction, confining potential and the number of electrons. The magnetic phase diagram of quantum dots, doped with a large number of magnetic Mn impurities, can be described by the energy- gap in the spectrum of electrons and the mean field electron - Mn exchange coupling. A competition between these two parameters leads to a transition between spin- unpolarized and spin- polarized states, in the absence of applied magnetic field. Tuning the energy- gap by electrostatic control of nonparabolicity of the confining potential can enable control of magnetization even at the fixed number of electrons. We illustrate our findings by directly comparing Mn- doped quantum dots with parabolic and Gaussian confining potential.