Failure of standard approximations of the exchange coupling in nanostructures

Jesper Pedersen*, Christian Flindt, Niels Asger Mortensen, Antti Pekka Jauho

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

31 Citations (Scopus)

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
Article number125323
Pages (from-to)1-6
Number of pages6
JournalPhysical Review B
Volume76
Issue number12
DOIs
Publication statusPublished - 28 Sep 2007
MoE publication typeA1 Journal article-refereed

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