Dynamics of nuclear polarization in InGaAs quantum dots in a transverse magnetic field
Dynamics of nuclear polarization in InGaAs quantum dots in a transverse magnetic field
复制标题
横向磁场中 InGaAs 量子点核极化动力学
DOI：
10.1134/s1063776112040176
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发表时间：
2012
影响因子：
1.1
通讯作者：
M. Bayer
中科院分区：
文献类型：
--
作者：
S. Verbin;I. Gerlovin;I. Ignatiev;M. S. Kuznetsova;R. Cherbunin;K. Flisinski;D. Yakovlev;M. Bayer
研究了带负电荷的InGaAs/GaAs量子点的时间分辨Hanle效应。用一种新颖的方法分析了实验数据，分离了核极化的纵向和横向分量的行为。这使得有可能确定核极化的每个分量的上升和衰减时间，以及它们与横向磁场强度的关系。核极化纵向分量(平行于外加磁场)的上升和下降时间几乎相等(约5ms)。对核极化横向分量的分析表明，相应的上升和下降时间差别很大，并且强烈依赖于磁场强度，当外加磁场在20到100mT之间时，从几毫秒增加到几十毫秒。目前的唯象模型不能解释观察到的核极化行为。在强四极分裂条件下，量子点的核自旋系统需要建立一个合适的自旋动力学理论才能找到解释。
The time-resolved Hanle effect is examined for negatively charged InGaAs/GaAs quantum dots. Experimental data are analyzed by using an original approach to separate behavior of the longitudinal and transverse components of nuclear polarization. This made it possible to determine the rise and decay times of each component of nuclear polarization and their dependence on transverse magnetic field strength. The rise and decay times of the longitudinal component of nuclear polarization (parallel to the applied field) were found to be almost equal (approximately 5 ms). An analysis of the transverse component of nuclear polarization shows that the corresponding rise and decay times differ widely and strongly depend on magnetic field strength, increasing from a few to tens of milliseconds with an applied field between 20 and 100 mT. Current phenomenological models fail to explain the observed behavior of nuclear polarization. To find an explanation, an adequate theory of spin dynamics should be developed for the nuclear spin system of a quantum dot under conditions of strong quadrupole splitting.