Electronic states in a magnetic quantum-dot molecule: phase transitions and spontaneous symmetry breaking

Abstract

We show that a double quantum-dot system made of diluted magnetic semiconductor behaves unlike usual molecules. In a semiconductor double quantum dot or in a diatomic molecule, the ground state of a single carrier is described by a symmetric orbital. In a magnetic material molecule, new ground states with broken symmetry can appear due the competition between the tunnelling and magnetic polaron energy. With decreasing temperature, the ground state changes from the normal symmetric state to a state with spontaneously broken symmetry. Interestingly, the symmetry of a magnetic molecule is recovered at very low temperatures. A magnetic double quantum dot with broken-symmetry phases can be used a voltage-controlled nanoscale memory cell.

4 pages, 5 figures

References in corpus (7)

• Direct Observation of Controlled Coupling in an Individual Quantum Dot Molecule
• Ferromagnetism mediated by few electrons in a semimagnetic quantum dot
• Single exciton spectroscopy of semimagnetic quantum dots
• Optically Induced Magnetization of CdMnTe Self-Assembled Quantum Dots
• Voltage-tunable ferromagnetism in semimagnetic quantum dots with few particles: magnetic polarons and electrical capacitance
• Selective optical manipulation of the spin state of a single magnetic impurity in a semiconductor quantum dot
• Self Assembled II-VI Magnetic Quantum Dot as a Voltage-Controlled Spin-Filter

Cited by in corpus (6)

• Magnetism in Closed-shell Quantum Dots: Emergence of Magnetic Bipolarons
• Reentrant Formation of Magnetic Polarons in Quantum Dots
• Magnetic phases of one-dimensional lattices with 2 to 4 fermions per site
• Nodal "ground states" and orbital textures in semiconductor quantum dots
• Para-ortho transition of artificial H${}_2$ molecule in lateral quantum dots doped with magnetic impurities
• Magnetism of quantum dot clusters: A Hubbard model study