Edge States in Two-Dimensional Electron Gas Systems at High Magnetic Fields Studies in Terms Spectroscopic Approach.

高磁场二维电子气系统中的边缘态光谱方法研究。

• 批准号: 05402012
• 负责人: KOMIYAMA Susumu
• 金额: $ 16.38万
• 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: 1993
• 资助国家: 日本
• 起止时间: 1993 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-05402012/
• 关键词: Quantum Hall Effects; Edge states; Cyclotron emission; Edge current; Dispersion relation of edge states; Breakdown of the Quantum Hall effects; Dissipation in quantum Hall devices; サイクロトロン共鳴吸収; 量子ホール効果のブレークダウン; 化学ポテンシャル・エッジ電流; ホール電流; 量子ホール効果状態

1. Dispersion relation of edge states : Transport characteristics associated with non-equilibrium edge state distribution indicated that the edge states consist of compressible and incompressible regions at low T below 0.1K but the dispersion smoothes with increasing T up to 0.5K at B=3T.2. Edge states and bulk states : A consistent calculation taking the excess edge charges into account derived the ratio between the edge current due to chemical potential and the Hall current due to electrostatic potential. Also, the "response current" due to all the electrons responding to the imposed perturbation was distinguished from the "Fermi-surface current" due to the current of the probability amplitude of the electrons on the Fermi surface. These two are alternative definitions of transport current, which lead to the bulk picture and the edge picture of the quantized Hall effedts (QHE), respectively.Mechanism and location of energy dissipation in the Quantum Hall effects (QHE)(1) Ultra-high sensitive detectors in the far-infrared (FIR) range were developed to make the aimed studies possible. By using QHE devices, a sensitivity by more than three orders of magnitude higher than that of the conventional Ge photoconductive detectors was achieved.(2) The cyclotron emission from dissipation-less two-demensional electron gas (2DEG) in the QHE regime was detected by the detectors above. Studies on an array of more than 3000 small Hall bars revealed that there is a threshold Hall voltage for the emission ; eV_H=homega_c/2. The results show that the emission is associated with the injection of electrons from contacts, and contributed to better understanding of the mechanism of exchange of electrons between contacts and the 2DEG system.4. Nonlocal nature of the breakdown of the QHE : Studies of spatial evolution of longitudinal electric field in Hall bars indicated that the bootstrap-type electron heating causes the QHE to breakdown.

1.边缘态的色散关系：与非平衡边缘态分布相关的输运特性表明，在低于0.1 K的低T下，边缘态由可压缩和不可压缩区域组成，但在B= 3 T时，色散随T的增加而平滑，直到0.5 K。边缘状态和体状态：考虑到过量边缘电荷的一致性计算得出了由于化学势引起的边缘电流与由于静电势引起的霍尔电流之间的比率。此外，“响应电流”，由于所有的电子响应于所施加的扰动是区别于“费米面电流”，由于在费米面上的电子的概率振幅的电流。量子霍尔效应（QHE）中能量耗散的机理和位置（1）研制了远红外超高灵敏度探测器，实现了对量子霍尔效应（QHE）的研究。通过使用QHE器件，实现了比常规Ge光电导探测器高三个数量级以上的灵敏度。(2)用上述探测器探测了QHE区无耗散二维电子气的回旋辐射。对超过3000个小霍尔条的阵列的研究表明，存在用于发射的阈值霍尔电压; eV_H=homega_c/2。结果表明，这种发射与接触电子的注入有关，有助于更好地理解接触和2DEG系统之间的电子交换机制. QHE击穿的非局域性质：霍尔条中纵向电场的空间演化研究表明，自举型电子加热导致QHE击穿。

项目成果

H.Hirai,: "Dependence of inter-edge-channel scattering on the temperature and magnetic field:Insight into the edge-confining potential." Phys.Rev.B. 52. 11159-11164 (1995)

H.Hirai：“边缘通道间散射对温度和磁场的依赖性：洞察边缘限制潜力。”

S.Komiyama: "Two Representations of the Current Density in Charge-Transport Problems." Phys.Rev.B. 54. 2067-2090 (1996)

S.Komiyama：“电荷传输问题中电流密度的两种表示。”

H.Hirai: "Phase-Coherence Length in a Two-Dimensional Electron Gas at High Magnetic Fields." Physica B. 184. 34-37 (1993)

H.Hirai：“高磁场下二维电子气的相位相干长度。”

H.Hirai,S.Komiyama: "Ratio between edge and bulk currents in teh quantum Hall effect" Physical Review B. 49. 14012-14015 (1994)

H.Hirai,S.Komiyama：“量子霍尔效应中的边缘电流和体电流之比”物理评论 B.49. 14012-14015 (1994)

H.Hirai: "Local Current Distribution in the Presence of Nonequilibrium Distribution of Edge States″" Jpn.J.Applc.Phys.34. 4321-4324 (1995)

H.Hirai：“存在边缘态非平衡分布的局部电流分布”Jpn.J.Applc.Phys.34 (1995)。