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arXiv 2301.04583cond-mat.mes-hall
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电荷可调量子点的磁光学:负抗磁位移的观测

Magneto-optics of a charge-tunable quantum dot: Observation of a negative diamagnetic shift

Giora Peniakov, Ayal Beck, Eilon Poem, Zu-En Su, Boaz Taitler, Sven Hoefling, Garnett. W. Bryant, David Gershoni

AI总结:

本文研究中性与正电自组装量子点的磁光响应,结合 Hartree–Fock 与扩展谐振势模型解释显著负抗磁位移,并提取介电常数、尺寸及 g 因子以确定 InGaAs 组分。

摘要:

我们展示了对处于中性和带正电状态的自组装半导体量子点的磁光学研究。精确测量了许多已明确识别的光学跃迁的抗磁位移和塞曼分裂。值得注意的是,在由双正电激子复合物产生的谱线中观测到了显著的负抗磁位移。我们采用 Hartree–Fock 近似来描述不同构型下量子点受限载流子之间的直接库仑相互作用和交换相互作用。随后,使用一个简单的谐振势模型来定量解释所有测得的抗磁位移;我们对该模型进行了扩展,以纳入 Faraday 构型下外加磁场的影响。我们表明,负位移源于磁场诱导的空穴–空穴交换相互作用能变化。利用该模型和测得的位移,我们提取了量子点材料的介电常数,并对量子点尺寸获得了合理估计。此外,各谱线测得的塞曼分裂也可通过一个简单模型解释,该模型使用处于各自第一和第二离散能级的受限载流子的 g 因子的代数和与差。最后,所得电子 g 因子和介电常数的数值被独立用于确定三元 In_xGa_{1-x}As 量子点的有效组分(x)。二者在实验不确定度范围内一致。

英文摘要:

We present magneto-optical studies of a self-assembled semiconductor quantum dot in neutral and positively charged states. The diamagnetic shifts and Zeeman splitting of many well-identified optical transitions are precisely measured. Remarkably, a pronounced negative diamagnetic shift is observed for spectral lines resulting from a doubly positively charged excitonic complex. We use the Hartree - Fock approximation for describing the direct Coulomb and exchange interactions between the quantum dot confined carriers in various configurations. A simple harmonic potential model, which we extend to capture the influence of an externally applied magnetic field in Faraday configuration, is then used to quantitatively account for all the measured diamagnetic shifts. We show that the negative shift is due to the change in the hole-hole exchange interaction energy induced by the magnetic field. Using this model and the measured shifts we extract the dielectric constant of the quantum dot material and get a decent estimate of the quantum dot dimensions. Further, the measured Zeeman splitting of the various spectral lines are also explained by a simple model using algebraic sums and differences of the $g$-factors of the confined charge carriers in their respective first and second discrete energy levels. Finally, the obtained values of the electronic $g$-factor and that of the dielectric constant are independently used to determine the effective composition (x) of the ternary In$_{x}$Ga$_{1-x}$As quantum dot. Both agree to within the experimental uncertainties.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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