Singlet-triplet ground-state instability in square quantum dot

Yuki Negishi, Masamu Ishizuki, Atsushi Tsubaki, Kyozaburo Takeda, Yusuke Asari, Takahisa Ohno

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    We theoretically study the spin multiplicity in the ground state of the square quantum dot (SQD) including four electrons, and discuss a possibility of the singlet-triplet (S/T) instability in the quantum system. As predicted by Hund's rule, the ground-state triplet appears when the DQD has a point group symmetry of D 4h. This ground-state triplet is also found even in the deformed SQD (D 2h) if the confinement length L is elongated. Consequently, the S/T instability is expected along these boundary lines. It is also worthwhile to notice that the present DFT as well as UHF calculation predicts the spin-singlet ground-state when the inter-electron interaction is strengthened (larger L) even though the SQD maintains its geometrical form of D 4h. The strong electron-localization causes the destabilization in the orbital (kinetic) energies, and produces this characteristic "anti-Hund" state.

    Original languageEnglish
    Title of host publicationAIP Conference Proceedings
    Pages497-498
    Number of pages2
    Volume1399
    DOIs
    Publication statusPublished - 2011
    Event30th International Conference on the Physics of Semiconductors, ICPS-30 - Seoul
    Duration: 2010 Jul 252010 Jul 30

    Other

    Other30th International Conference on the Physics of Semiconductors, ICPS-30
    CitySeoul
    Period10/7/2510/7/30

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    Keywords

    • DFT
    • Hund's rule
    • quantum dot
    • singlet-triplet instability
    • UHF

    ASJC Scopus subject areas

    • Physics and Astronomy(all)

    Cite this

    Negishi, Y., Ishizuki, M., Tsubaki, A., Takeda, K., Asari, Y., & Ohno, T. (2011). Singlet-triplet ground-state instability in square quantum dot. In AIP Conference Proceedings (Vol. 1399, pp. 497-498) https://doi.org/10.1063/1.3666471