Hyperfine-Induced Electron-Spin Dephasing in Negatively Charged Colloidal Quantum Dots: A Survey of Size Dependence,The Journal of Physical Chemistry Letters

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Hyperfine-Induced Electron-Spin Dephasing in Negatively Charged Colloidal Quantum Dots: A Survey of Size Dependence
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2021-09-24 , DOI: 10.1021/acs.jpclett.1c02754
Yuanyuan Zhang ₁ , Meizhen Jiang ₁ , Zhen Wu ₁ , Qing Yang ₁ , Yumeng Men ₁ , Lin Cheng ₁ , Pan Liang ₂ , Rongrong Hu ₃ , Tianqing Jia ₁ , Zhenrong Sun ₁ , Donghai Feng _{1,

4}

Affiliation

The electron spin relaxation processes are complicated in semiconductor quantum dots. Different spin relaxation mechanisms may result in an increased or decreased spin relaxation rate with the size. The information on size-dependent spin dynamics helps to clarify and better understand the underlying spin relaxation processes. We investigate the size dependence of the electron spin dynamics in negatively photocharged CdSe and CdS colloidal quantum dots by time-resolved ellipticity spectroscopy. It is revealed that the electron spin dephasings of photodoped electron in zero or weak magnetic fields are dominated by the electron–nuclear hyperfine interaction for all measured samples. The hyperfine-induced electron spin dephasing time is ∼1–2 ns at room temperature and decreases with decreasing the size D. In addition to a size-dependent dephasing time that is directly proportional to D^3/2, our measurements also show a size-independent time component, likely due to the laser-induced nuclear spin ordering.

中文翻译：

带负电荷的胶体量子点中的超精细诱导电子自旋移相：尺寸依赖性调查

半导体量子点中的电子自旋弛豫过程是复杂的。不同的自旋弛豫机制可能导致自旋弛豫率随尺寸增加或减少。与尺寸相关的自旋动力学信息有助于阐明和更好地理解潜在的自旋弛豫过程。我们通过时间分辨椭圆度光谱研究了带负光电荷的 CdSe 和 CdS 胶体量子点中电子自旋动力学的大小依赖性。结果表明，对于所有测量样品，光掺杂电子在零磁场或弱磁场中的电子自旋移相由电子 - 核超精细相互作用主导。超精细诱导的电子自旋移相时间在室温下为~1-2 ns，并随着尺寸D 的减小而减小. 除了与D ^3/2成正比的与尺寸相关的去相时间之外，我们的测量还显示出与尺寸无关的时间分量，这可能是由于激光诱导的核自旋排序。

更新日期：2021-10-07

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