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Quantum Transport in Two-Dimensional Electron Systems in Super Periodic Structures

超周期结构二维电子系统中的量子输运

基本信息

批准号：
13304025
负责人：
IYE Yasuhiro
金额：
$ 20.55万
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 (A)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2004
项目状态：
已结题

项目摘要

We carried out a systematic study of quantum oscillatory phenomena in triangular antidot lattices based on two-dimensional electron gas(2DEG) at semiconductor heterointerface. We have observed three different types of quantum interference effects, ---Altshuler-Aronov-Spivak(AAS) oscillation and Aharonov-Bohm(AB) type oscillation near zero field and another type of AB-type oscillation in the quantum Hall regime. We measured their temperature dependences, and elucidated the differences in the decoherence mechanisms. The gate bias dependence of the high field AB-type oscillation furnished information on the self-consistent screened potential formed around the antidots.We studied electron transport under spatial gradient of magnetic field in 2DEG quantum wire decorated with mesoscopic ferromagnetic wire, and found (1)asymmetric conduction and rectifying effect, (2)universal conductance fluctuation in spatially varying magnetic field, and (3)magnetic barrier effect in the quantum Hall regim … More e.We have uncovered a novel magnetoresistance oscillation in short period unidirectional lateral superlattices, which occurred in the lower magnetic field range than the so-called commensurability oscillations. From the analysis of its dependence on the electron density and modulation period, we concluded that the phenomenon is due to geometrical resonance of open orbits with the modulation period. The open orbits are created by Bragg reflection from the lateral superlattice, so this is a clear demonstration of the mini-gap formation. We have also established the method to quantify the modulation amplitude at the 2DEG plane from the analysis of the commensurability oscillation of magnetoresistance.The Little-Parks oscillation of a superconducting wire network subjected to a spatially alternating magnetic flux pattern was investigated. The evolution of the oscillation pattern as a function of the amplitude of the alternation field and that of the uniform field was shown to agree well with the spectral edge of the corresponding Hofstadter butterflies. Less

我们对基于半导体异质界面二维电子气（2DEG）的三角解点晶格中的量子振荡现象进行了系统研究。我们观察到了三种不同类型的量子干涉效应，即Altshuler-Aronov-Spivak（AAS）振荡和近零场的Aharonov-Bohm（AB）型振荡以及量子霍尔区域中的另一种AB型振荡。我们测量了它们的温度依赖性，并阐明了退相干机制的差异。高场AB型振荡的栅极偏压依赖性提供了关于反点周围形成的自洽屏蔽电势的信息。我们研究了介观铁磁线装饰的2DEG量子线中磁场空间梯度下的电子传输，发现(1)不对称传导和整流效应，(2)空间变化磁场中的普遍电导涨落，以及 (3)量子霍尔区域中的磁势垒效应 e.我们在短周期单向横向超晶格中发现了一种新型磁阻振荡，它发生在比所谓的可通约性振荡更低的磁场范围内。通过分析其对电子密度和调制周期的依赖性，我们得出结论，该现象是由于开放轨道与调制周期的几何共振所致。开放轨道是由横向超晶格的布拉格反射创建的，因此这是迷你间隙形成的清晰演示。通过对磁阻可通约振荡的分析，我们还建立了量化2DEG平面调制幅度的方法。研究了超导线网络在空间交变磁通量模式下的Little-Parks振荡。振荡模式的演变作为交变场和均匀场幅度的函数，与相应的霍夫施塔特蝴蝶的光谱边缘非常吻合。较少的