Ellipsoidal deformation of vertical quantum dots

D. G. Austing, S. Sasaki, S. Tarucha, S. M. Reimann, M. Koskinen, and M. Manninen
Phys. Rev. B 60, 11514 – Published 15 October 1999
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Abstract

Addition energy spectra at 0 T of circular and ellipsoidally deformed few-electron vertical quantum dots are measured and compared to results of model calculations within spin-density-functional theory. Because of the rotational symmetry of the lateral harmonic confining potential, circular dots show a pronounced shell structure. With the lifting of the single-particle level degeneracies, even a small deformation is found to radically alter the shell structure leading to significant modifications in the addition energy spectra. Breaking the circular symmetry with deformation also induces changes in the total spin. This “piezomagnetic” behavior of quantum dots is discussed, and the addition energies for a set of realistic deformation parameters are provided. For the case of the four-electron ground state at 0 T, a spin-triplet to spin-singlet transition is predicted, i.e., Hund’s first rule no longer applies. Application of a magnetic field parallel to the current confirms that this is the case, and also suggests that the anisotropy of an elliptical dot, in practice, may be higher than that suggested by the geometry of the device mesa in which the dot is located.

  • Received 17 May 1999

DOI:https://doi.org/10.1103/PhysRevB.60.11514

©1999 American Physical Society

Authors & Affiliations

D. G. Austing*, S. Sasaki, and S. Tarucha

  • NTT Basic Research Laboratories, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198, Japan

S. M. Reimann, M. Koskinen, and M. Manninen

  • Physics Department, University of Jyväskylä, P.O. Box 35, 40351 Jyväskylä, Finland

  • *Electronic address: austing@will.brl.ntt.co.jp
  • Present address: Physics Department, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
  • Electronic address: reimann@phys.jyu.fi

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Issue

Vol. 60, Iss. 16 — 15 October 1999

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