Electronic States of Magnetic Quantum Dots

TL;DR

This paper investigates the electronic and magnetic properties of Mn-doped quantum dots, revealing how exchange interactions and confinement influence spin states and enabling electrostatic control of magnetization.

Contribution

It introduces a detailed analysis of magnetic phase transitions in quantum dots, highlighting the role of energy gap tuning via confining potential shape.

Findings

Transition between spin states driven by exchange coupling and energy gap.

Electrostatic control can modulate magnetization at fixed electron number.

Comparison of different confining potentials shows impact on magnetic behavior.

Abstract

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.