Failure of standard approximations of the exchange coupling in nanostructures

Jesper Goor Pedersen, Christian Flindt, Asger Mortensen, Antti-Pekka Jauho

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Abstract

We calculate the exchange coupling for a double dot system using a numerically exact technique based on finite-element methods and an expansion in two-dimensional Gaussians. Specifically, we evaluate the exchange coupling both for a quasi-one- and a two-dimensional system, also including an applied magnetic field. Our numerical results provide a stringent test of standard approximation schemes e.g., Heitler-London, Hund- Mulliken, Hubbard, and they show that the standard methods do not have reliable predictive power even for simple model systems. Their value in modeling more realistic quantum-dot structures is thus cast in serious doubt.
Original languageEnglish
JournalPhysical Review B (Condensed Matter and Materials Physics)
Volume76
Issue number12
Pages (from-to)125323
ISSN1098-0121
DOIs
Publication statusPublished - 2007
Externally publishedYes

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Exchange coupling
Nanostructures
approximation
Semiconductor quantum dots
casts
finite element method
quantum dots
Magnetic fields
Finite element method
expansion
magnetic fields

Cite this

Pedersen, Jesper Goor ; Flindt, Christian ; Mortensen, Asger ; Jauho, Antti-Pekka. / Failure of standard approximations of the exchange coupling in nanostructures. In: Physical Review B (Condensed Matter and Materials Physics). 2007 ; Vol. 76, No. 12. pp. 125323.
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Failure of standard approximations of the exchange coupling in nanostructures. / Pedersen, Jesper Goor; Flindt, Christian; Mortensen, Asger; Jauho, Antti-Pekka.

In: Physical Review B (Condensed Matter and Materials Physics), Vol. 76, No. 12, 2007, p. 125323.

Research output: Contribution to journalJournal articleResearchpeer-review

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AB - We calculate the exchange coupling for a double dot system using a numerically exact technique based on finite-element methods and an expansion in two-dimensional Gaussians. Specifically, we evaluate the exchange coupling both for a quasi-one- and a two-dimensional system, also including an applied magnetic field. Our numerical results provide a stringent test of standard approximation schemes e.g., Heitler-London, Hund- Mulliken, Hubbard, and they show that the standard methods do not have reliable predictive power even for simple model systems. Their value in modeling more realistic quantum-dot structures is thus cast in serious doubt.

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