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
    Volume76
    Issue number12
    Pages (from-to)125323
    ISSN0163-1829
    DOIs
    Publication statusPublished - 2007

    Bibliographical note

    Copyright 2007 American Physical Society

    Keywords

    • DOUBLE-QUANTUM DOTS

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