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首页> 外文期刊>Japanese journal of applied physics >Ground State Instability in Spin Polarization for Electrons Confined in Two-Dimensional Square Quantum Dots
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Ground State Instability in Spin Polarization for Electrons Confined in Two-Dimensional Square Quantum Dots

机译：二维正方形量子点中电子自旋极化的基态不稳定性

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摘要

We present a theoretical study of the ground state electronic structure and the spin polarization for four electrons confined in two-dimensional (2D) square quantum dots (SQDs). We employ standard mean field theory (MFT) approaches using the unrestricted Hartree-Fock (UHF) and density functional theory calculations. The resonant UHF configuration interaction (res-UHF Cl) calculation was also performed in order to incorporate the electron correlation more intuitively. The MFT ground state is expected to be spin-polarized when SQDs have a small confinement length L or aspect ratio δ = L_x/L_y = 1, in agreement with Hund's rule. In contrast, the spin-unpolarized ground state singlet is expected in all in other SQDs. Thus, the MFT calculations produce the anti-Hund state, where the spin-density wave forms having the zero of the total spin, even though the SQD has the point group symmetry D_4h· However, the res-UHF Cl calculation restores the geometrical symmetry in the resulting ground state when the Coulomb interaction is strengthened. Nevertheless, the res-UHF Cl ground state maintains the zero total spin. Thus, ground state instability is expected in the spin-polarization of the SQD system, which eventually violates Hund's rule in accordance with the Coulomb interaction.
机译：我们目前对二维电子（2D）方形量子点（SQDs）中限制的四个电子的基态电子结构和自旋极化进行理论研究。我们采用无限制Hartree-Fock（UHF）和密度泛函理论计算的标准均场理论（MFT）方法。为了更直观地合并电子相关性，还进行了共振UHF组态相互作用（res-UHF Cl）计算。当SQD的约束长度L小或纵横比δ= L_x / L_y = 1时，MFT基态有望自旋极化，这与洪德定律一致。相比之下，其他所有SQD中都期望自旋非极化基态单重态。因此，即使SQD具有点群对称D_4h，MFT计算也会产生反洪德状态，其中自旋密度波形的总自旋为零。然而，res-UHF Cl计算恢复了几何对称性当库仑相互作用增强时，在最终的基态中然而，res-UHF Cl基态保持总自旋为零。因此，在SQD系统的自旋极化中可能会出现基态不稳定性，这最终违反了根据库仑相互作用的洪德法则。

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  • 来源
    《Japanese journal of applied physics》 |2011年第8issue1期|p.085001.1-085001.12|共12页
  • 作者

    Yhuki Negishi; Masamu Ishizuki; Takuma Okunishi; Kyozaburo Takeda;

  • 作者单位

    Department of Electrical Engineering and Bioscience, Graduate School of Advanced Science and Engineering,Waseda University, Shinjuku, Tokyo 169-8555, Japan;

    Department of Electrical Engineering and Bioscience, Graduate School of Advanced Science and Engineering,Waseda University, Shinjuku, Tokyo 169-8555, Japan;

    Department of Electrical Engineering and Bioscience, Graduate School of Advanced Science and Engineering,Waseda University, Shinjuku, Tokyo 169-8555, Japan;

    Department of Electrical Engineering and Bioscience, Graduate School of Advanced Science and Engineering,Waseda University, Shinjuku, Tokyo 169-8555, Japan;

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