Spin configurations in circular and rectangular vertical quantum dots in a magnetic field: Three-dimensional self-consistent simulations

Dmitriy V. Melnikov, Philippe Matagne, Jean-Pierre Leburton, D. G. Austing, G. Yu, S. Tarucha, John Fettig, and Nahil Sobh
Phys. Rev. B 72, 085331 – Published 16 August 2005

Abstract

The magnetic field dependence of the electronic properties of real single vertical quantum dots in circular and rectangular mesas is investigated within a full three-dimensional multiscale self-consistent approach without any á priori assumptions about the shape and strength of the confinement potential. The calculated zero field electron addition energies are in good agreement with available experimental data for both mesa geometries. Charging diagrams in a magnetic field for number of electrons up to five are also computed. Consistent with the experimental data, we found that the charging curves for the rectangular mesa dot in a magnetic field are flatter and exhibit less features than for a circular mesa dot. Evolution of the singlet-triplet energy separation in the two electron system for both dot geometries in magnetic field was also investigated. In the limit of large field, beyond the singlet-triplet transition, the singlet-triplet energy difference continues to become more negative in a circular mesa dot without any saturation within the range of considered magnetic fields while it is predicted to asymptotically approach zero for the rectangular mesa dot. This different behavior is attributed to the symmetry “breaking” that occurs in the singlet wave-functions in the rectangular mesa dot but not in the circular one.

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  • Received 3 March 2005

DOI:https://doi.org/10.1103/PhysRevB.72.085331

©2005 American Physical Society

Authors & Affiliations

Dmitriy V. Melnikov, Philippe Matagne, and Jean-Pierre Leburton

  • Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 401 North Mathews Avenue, Urbana, Illinois 61801, USA

D. G. Austing and G. Yu

  • Institute for Microstructural Sciences, National Research Council of Canada, Montreal Road, Ottawa, Ontario K1A 0R6, Canada

S. Tarucha*

  • Tarucha Mesoscopic Correlation Project, ERATO, JST, Atsugi-shi, Kanagawa 243-0198, Japan

John Fettig and Nahil Sobh

  • National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, 401 North Mathews Avenue, Urbana, Illinois 61801, USA

  • *Also at the Department of Applied Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.

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Issue

Vol. 72, Iss. 8 — 15 August 2005

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