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Phase coherence and its control of quantum Hall electron systems

量子霍尔电子系统的相位相干性及其控制

基本信息

批准号：
10440101
负责人：
KOMIYAMA Susumu
金额：
$ 9.28万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10440101/
关键词：
quantum Hall effects resistance fluctuation fractional edge states spin polarization of edge states double quantum dots inelastic scattering scattering-wave states 位相干渉性伝導度ゆらぎ AB効果

项目摘要

[Resistance fluctuation] GaAs/AlGaAs heterostructure devices, in which two small scattering regions are connected with a quantum Hall electron system, has been studied. The longitudinal resistance is found to exhibit fluctuations in transition regions between successive integer quantum Hall (IQH) states at temperatures below 100mK.The analysis shows that (i) the electron system is coherent over the entire region of the devices, and (ii) the resistance fluctuation arises from the fact that the electron system in transition regions splits into isolated incompressible regions fringed by a network of compressible strips.[Inelastic scattering process] Source-drain voltage dependence of the transition width between IQH states, studied on GaAs/AlGaAs haterostructure devices, revealed that (i) the eigen-states of the electron system are the scattering-wave-states incident from the source and the drain electrodes, and that (ii) the inelastic scattering process between the respective scattering-wave-states is strongly suppressed in the transition regions. This provided the basis for explaining the much longer inelastic scattering lengths found in strong magnetic fields.[Inter-edge-state scattering : Spin polarization] In odd IQH states and in fractional QH states (2/3 and 1/3), remarkable hysteresis behavior was found in the inter-edge-state scattering process. The effects are interpreted by assuming that nuclear spin is induced by the flip of electron spin and the induced nuclear spin significantly increases an effective magnetic field for the electron spin through the hyperfine interaction. In the case of the fractional QH states, this particularly implies that (i) fractional edge states exist and (ii) the fractional edge states have respective spin polarizations.[Breakdown phenomena of IQH states] The mechanism of the current-induced breakdown of IQH states was clarified in terms of a heat instability of IQH electron systems.

[电阻起伏] GaAs/AlGaAs异质结器件，其中两个小的散射区与一个量子霍尔电子系统相连，已被研究。发现在低于100 mK的温度下，纵向电阻在连续整数量子霍尔（IQH）态之间的过渡区出现涨落，分析表明：（i）电子系统在器件的整个区域内是相干的，以及（ii）电阻波动是由于过渡区中的电子系统分裂成孤立的不可压缩区，这些不可压缩区由可压缩网络包围。脱衣舞[非弹性散射过程]在GaAs/AlGaAs异质结器件上研究了IQH态之间的跃迁宽度与源漏电压的关系，揭示了（i）电子系统的本征态是从源极和漏极入射的散射波态，并且（ii）各个散射波态之间的非弹性散射过程在过渡区被强烈抑制。这为解释在强磁场中发现的更长的非弹性散射长度提供了基础。[边缘态间散射：自旋极化]在奇IQH态和分数QH态（2/3和1/3）中，在边缘态间散射过程中发现了显著的滞后行为。这种效应是通过假设核自旋是由电子自旋的翻转引起的，并且所引起的核自旋通过超精细相互作用显著地增加了电子自旋的有效磁场来解释的。在分数QH状态的情况下，这特别意味着（i）分数边缘状态存在，以及（ii）分数边缘状态具有相应的自旋极化。[IQH态的击穿现象]根据IQH电子系统的热不稳定性，阐明了IQH态的电流诱导击穿机制。