Vertically coupled double quantum dots in magnetic fields

Abstract

Ground-state and excited-state properties of vertically coupled double quantum dots are studied by exact diagonalization. Magic-number total angular momenta that minimize the total energy are found to reflect a crossover between electron configurations dominated by intra-layer correlation and ones dominated by inter-layer correlation. The position of the crossover is governed by the strength of the inter-layer electron tunneling and magnetic field. The magic numbers should have an observable effect on the far infra-red optical absorption spectrum, since Kohn's theorem does not hold when the confinement potential is different for two dots. This is indeed confirmed here from a numerical calculation that includes Landau level mixing. Our results take full account of the effect of spin degrees of freedom. A key feature is that the total spin, $S$, of the system and the magic-number angular momentum are intimately linked because of strong electron correlation. Thus $S$ jumps hand in hand with the total angular momentum as the magnetic field is varied. One important consequence of this is that the spin blockade (an inhibition of single-electron tunneling) should occur in some magnetic field regions because of a spin selection rule. Owing to the flexibility arising from the presence of both intra-layer and inter-layer correlations, the spin blockade is easier to realize in double dots than in single dots.

to be published in Phys. Rev. B15

References in corpus (7)

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• Correlated few-electron states in vertical double-quantum-dot systems
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• Composite-Fermion Analysis of the Double-Layer Fractional Quantum Hall System
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• Molecular phases in coupled quantum dots
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• Raman signatures of classical and quantum phases in coupled dots: A theoretical prediction
• Effective interactions and large-scale diagonalization for quantum dots
• Charge-localization and isospin-blockade in vertical double quantum dots
• Canted phase in double quantum dots
• Electron-hole bilayer quantum dots: Phase diagram and exciton localization
• Spin Hot Spots in vertically-coupled Few-electron Quantum Dots
• Classical electrons in laterally coupled diatomic 2D artificial molecule
• Quantum phases of correlated electrons in artificial molecules under magnetic fields
• Incompressible States in Double Quantum Dots
• Isospin Blockade in Transport through Vertical Double Quantum Dots
• The Stability of the Quantum Hall State at $\nu =1$ in Bilayer Electron Systems