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Phys. Rev. B 64, 085332 (2001) [8 pages]

Double quantum dot with two electrons: Singlet-triplet transitions

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O. Entin-Wohlman*
Center of Advanced Studies, Norwegian Academy of Sciences, Oslo 0271, Norway

Amnon Aharony
School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel

Y. Levinson
Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel

Received 5 March 2001; published 8 August 2001

The magnetic character of the ground state of two electrons on a double quantum dot, connected in series to left and right single-channel leads, is considered. By solving exactly for the spectrum of the two interacting electrons, it is found that the coupling to the continuum of propagating states on the leads, in conjunction with the electron-electron interactions, may result in a delocalization of the bound state of the two electrons. This, in turn, reduces significantly the range of the Coulomb interaction parameters over which singlet-triplet transitions can be realized. It is also found that the coupling to the leads favors the singlet ground state.

© 2001 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.64.085332
DOI:
10.1103/PhysRevB.64.085332
PACS:
73.23.Hk, 73.40.Gk, 73.20.Jc

*Permanent address: School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel.

 
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