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Investigation of the Macro Coherence in Bilayer Quantum Hall State by Micro Wave

微波研究双层量子霍尔态的宏观相干性

基本信息

批准号：
14340088
负责人：
SAWADA Anju
金额：
$ 10.05万
依托单位：
KYOTO UNIVERSITY (2004)Tohoku University (2002-2003)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14340088/
关键词：
Quantum Hall Effect Composite Boson Composite Fermion Interlayer Coherence Activation Energy Gallium Arsenide Pseudospin Spin

项目摘要

We investigated interlayer coherence of the bilayer quantum Hall states. The microwave cryostat was constructed for measurement of Josephson plasmon and then the experiments were done at 2 K. The quantum Hall effects were clearly observed, but Josephson plasmon was not observed. The cause we cannot observe Josephson plasmon is due to the low quality of the sample and the higher temperature. We will soon improve the experimental way to detect Josephson plasmon. The other hand, we get important experimental results for interlayer coherence from transport.(1) : We study a pseudospin (layer degree of freedom) domain structure in bilayer v=1 quantum Hall states by detailed transport measurements in tilted magnetic fields. We find that the magnetoresistance R_<xx> shows a broad peak at the commensurate-incommensurate transition. An extrapolated value of R_<xx> at the peak down to 0 K is finite, showing the existence of a dissipative ground state. From the comparison of B_<//> dependence of R_<xx> and activation energy with theories, we suggest that the origin of the dissipation is pseudospin domain walls in the soliton lattice. This is the first observation in the quantum Hall state that a resistance peak is induced not by the crossing of two Landau levels, but possibly by a number of pseudospin domains, i.e., interlayer phase twists.(2) : We examine an anisotropic transport in a bilayer system around the quantum Hall state at the total Landau level filling factor v=1. We find that the anisotropy becomes remarkable at the phase transition point between the commensurate and incommensurate states. This results that a unidirectional state appears around the transition.

我们研究了双层量子霍尔态的层间相干性。建立了用于测量约瑟夫森等离子体激元的微波低温恒温器，并在2 K下进行了实验。量子霍尔效应被清楚地观察到，但约瑟夫森等离子体没有被观察到。我们不能观测到约瑟夫森等离子体激元的原因是由于样品质量低和温度较高。我们将很快改进探测约瑟夫森等离子体激元的实验方法。另一方面，我们从输运中得到了层间相干的重要实验结果。(1)：通过在倾斜磁场中的详细输运测量，研究了双层v=1量子霍尔态中的伪自旋（层自由度）域结构。我们发现磁电阻R_<xx>在公度-不相称转变处有一个宽峰。在0 K以下的峰值处，外推的R_<xx>值是有限的，表明耗散基态的存在。从R_<xx>和活化能的B_<//>依赖性与理论的比较，我们认为耗散的起源是孤子晶格中的伪自旋畴壁。这是在量子霍尔态中第一次观察到，一个电阻峰不是由两个朗道能级的交叉引起的，而是可能由一些伪自旋域引起的，即层间相位扭曲。(2)：我们研究了在总朗道能级填充因子v=1时，量子霍尔态周围的双层系统中的各向异性输运。我们发现，在相称态和不相称态之间的相变点，各向异性变得显著。这导致在跃迁周围出现单向状态。