Magnetic anisotropy in symmetric magnetic colloidal quantum dots doped with few Mn(2+) impurities

Abstract

We present numerical exact diagonalization studies of the magnetism in magnetic II-VI colloidal semiconductor quantum dots charged with controlled number of electrons coupled to few magnetic-ion (Mn(2+)) dopants. The interplay between various relevant spin interactions and the discrete nature of Mn(2+) spin distribution is shown to be essential in the magnetism of few Mn(2+)-doped quantum dots. An interesting revealed feature is the existence of pronounced magnetic anisotropies in symmetric magnetic quantum dots, which are related to the orbital quenchings induced by electron-Mn spin interactions. The orbital quenching effects further lead to significant deviations of the magnetizations of randomly Mn-doped dots from the standard Brillouin-function descriptions.