Anderson transitions in disordered systems and electron correlations

无序系统中的安德森跃迁和电子关联

基本信息

批准号：
16540294
负责人：
KAWARABAYASHI Tohru
金额：
$ 2.05万
依托单位：
Toho University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

In 2004 and 2005, we have studied the transport properties of the two-dimensional system in a disordered magnetic field with a fixed sign. This model corresponds to the case where the random fluctuation of the magnetic field is of the same order of its mean value. The two-dimensional random magnetic field system arises in the theory of the fractional quantum Hall system where the electron correlation plays an important role. It has then been found for systems without edge states that the conductance is insensitive to the strength of the fluctuation of the magnetic field and stays on the order of the conductance quantum in the limit of weak magnetic fields. This singular behavior can be understood within the framework of the Drude formula. Apart from this classical singularity in the weak field limit, we have also shown that the Shubnikov-de Haas effect is clearly seen in this system.We have also investigated the statistical properties of the conductance in such a system. In particular, … More the critical conductance distribution has been analyzed in detail. In the presence of edge states, it has been shown that the critical distribution of conductance exhibits a wide distribution whose width is of the order of the conductance quantum. For systems with no edge state, the critical distribution similar to that for the network model and that for the model with potential disorder has been obtained, suggesting the universality of the critical distribution.In 2006, we have studied the effect of potential correlation in quantum Hall wires and found unexpected feature introduced by the potential correlation. In real materials, the impurity potential has a finite potential range and thus the disorder potential has a finite correlation length. It is therefore important to consider the effect of potential correlation as well as the electron correlation. In the absence of impurities, the conductance of the quantum Hall wire exhibits the quantized steps at the bulk Landau levels. In the presence of impurities, the impurity scattering mixes the edge states with the bulk states and the conductance becomes exponentially small at the conductance plateau transitions. We have found that when the potential correlation length is larger than the magnetic length, the small conductance region disappears as expected. Apart from it, we have also found unexpectedly that the conductance steps shift toward higher energies. This new feature is specific to long wires. We have argued semi-classically that the shift is a consequence of the reflection of edge states due to smoothly varying disorder potential. Less

2004年和2005年，我们研究了具有固定符号的无序磁场中二维系统的输运特性，该模型对应于磁场的随机涨落与其平均值同阶的情况。二维随机磁场系统出现在分数量子霍尔系统的理论中，其中电子相关性起着重要作用，然后发现对于没有边缘态的系统，电导对波动的强度不敏感。磁场在弱磁场极限下，这种奇异行为可以在德鲁德公式的框架内理解，除了弱场极限中的经典奇异性之外，我们还证明了舒布尼科夫-德哈斯效应在该系统中清晰可见。我们还研究了此类系统中电导的统计特性，特别是在存在边缘态的情况下详细分析了临界电导分布。表明电导的临界分布表现出宽分布，其宽度为电导量子量级，对于没有边缘态的系统，得到了与网络模型和潜在无序模型相似的临界分布，表明了临界分布的普遍性。 2006年，我们研究了量子霍尔线中势相关的影响，发现了势相关带来的意想不到的特征。在实际材料中，杂质势具有有限的势范围，因此无序势具有有限的相关长度。因此，重要的是要考虑在没有杂质的情况下，量子霍尔线的电导在体朗道能级上表现出量子化的阶跃。在有杂质的情况下，杂质散射将边缘态与边缘态混合。在电导平台跃迁处，体态和电导呈指数减小。除此之外，我们还意外地发现，当潜在相关长度大于磁长度时，小电导区域消失。这个新特征是长导线特有的，我们已经半经典地认为，这种转变是由于平滑变化的无序势而导致的边缘态反射的结果。

项目成果

期刊论文数量（14）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Shubnikov-de Haas effect on conductance fluctuations in two-dimensional random magnetic fields

二维随机磁场中电导涨落的舒布尼科夫-德哈斯效应

DOI：
发表时间：
2006
期刊：
Physica E 34
影响因子：
0
作者：
Y. Nagai;H. Akera and H. Suzuura;T.Kawarabayashi
通讯作者：
T.Kawarabayashi

Electron diffusion in a two-dimensional disordered symplectic system with electron-phonon interactions

具有电子-声子相互作用的二维无序辛系统中的电子扩散

DOI：
发表时间：
2005
期刊：
Journal of the Physical Society of Japan 74
影响因子：
0
作者：
S.Kanamaru;H.Suzuura;H.Akera;H.Watanabe
通讯作者：
H.Watanabe

Quantum transport properties of two-dimensional systems in disordered magnetic fields with a fixed sign

具有固定符号的无序磁场中二维系统的量子输运特性

DOI：
发表时间：
2005
期刊：
Physical Review B 71
影响因子：
0
作者：
S.Kanamaru;H.Suzuura;H.Akera;H.Watanabe;T. Ise;T.Kawarabayashi
通讯作者：
T.Kawarabayashi

Quantum transport pro perties of two-dimensional systems in disorder ed magnetic fields with a fixed sign

固定符号无序磁场中二维系统的量子输运特性

DOI：
发表时间：
2005
期刊：
Physical Review B 71
影响因子：
0
作者：
S.Kanamaru;H.Suzuura;H.Akera;H.Watanabe;T. Ise;T.Kawarabayashi;H. Akera;H.Watanabe et al.;T.Kawarabayashi et al.
通讯作者：
T.Kawarabayashi et al.