Failure of standard approximations of the exchange coupling in nanostructures

Jesper Pedersen, Christian Flindt, Niels Asger Mortensen, and Antti-Pekka Jauho
Phys. Rev. B 76, 125323 – Published 28 September 2007

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.

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  • Received 30 May 2007

DOI:https://doi.org/10.1103/PhysRevB.76.125323

©2007 American Physical Society

Authors & Affiliations

Jesper Pedersen1, Christian Flindt1, Niels Asger Mortensen1, and Antti-Pekka Jauho1,2

  • 1MIC—Department of Micro and Nanotechnology, NanoDTU, Technical University of Denmark, Building 345E, DK-2800 Kongens Lyngby, Denmark
  • 2Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, FI-02015 HUT, Finland

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Issue

Vol. 76, Iss. 12 — 15 September 2007

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