Integer Quantum Hall Effect in the Presence of Elastic Backscattering of Electrons

我们小组在三年前发现的边缘态的非平衡电子居群，激发了本研究项目。自这一发现以来，一种关于积分量子霍尔效应的新观点出现，在积分量子霍尔效应的理论认识和实验成就方面都有了显著的发展。目前的研究项目在研究领域快速、爆炸性增长的各个阶段都做出了实质性的贡献。主要成果如下：1)发现了非平衡电子分布引起的量子化霍尔电阻的显著偏差。2)理解电触点在产生和检测非平衡电子分布时所起的作用及其一般表述。3)积分量子霍尔效应精密测量中接触效应的定量分析。4)边间态电子散射分析及其对温度的依赖性。5)与非平衡居群相关的非线性输运效应分析：特别是对边缘态倒转电子居群的预测。6)提出了一种处理标准霍尔棒样品中非平衡总体的一般导体模型，并用该模型对实验结果进行了定量解释。7)提出了一种确定整数量子霍尔效应中相相干长度的可能实验。综上所述，本研究项目对二维电子气体在高磁场下的输运性质的认识有了显著提高。

A nonequilibrium population of electrons in edge states, discovered by our group three years ago, motivated the present research project. Since the discovery, a novel view of integral quantum Hall effects emerged to initiate remarkable developments both in theoretical understanding and in experimental achievements of integral quantum Hall effects. The present research project has made substantial contribution on each stage of the rapid and explosive growth of the research field. The achievements are summarized below :1) Discovery of remarkable deviation of quantized Hall resistance due to nonequilibrium electron distribution.2) Understanding and its general formulation of the role played by electrical contacts -when producing and detecting nonequilibrium electron distribution.3) Quantitative analysis of the effects of contacts in the precision measurements of integral quantum Hall effects.4) Analysis of inter-edge-state electron scattering and the understanding of its dependence on temperature.5) Analysis of nonlinear transport effects associated with the nonequilibrium population : Particularly, a prediction of inverted electron population in edge states.6) Proposal of a general model of conductors that treats nonequilibrium population in standard Hall-bar samples, and the quantitative explanation of experimental results by the model.7) Proposal of a possible experiments to determine phasecoherence length in a regime of integer quantum Hall effects.To summarize, the present research project has achieved remarkably improved understanding of the transport properties in two dimensional electron gas at high magnetic fields.