Macrocoherence in bilayer quantum Hall state

双层量子霍尔态的宏观相干性

• 批准号: 11304019
• 负责人: SAWADA Anju
• 金额: $ 22.27万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11304019/
• 关键词: Quantum Hall effect; Composite Boson; Activation energy; Interlayer coherence; Bose condensation; Gallium Arsenide; Pseudospin; Spin; 擬スピン; ホールプラトー; スカーミオン

Skyrmion excitations were measured and compared for the first time in the bilayer quantum Hall (QH) state at the Landau-level filling factor ν=2 and in the monolayer QH state at ν=1. The observed number of flipped spins, Ns, is 14 in the bilayer sample with a large tunneling gap, and Ns=7 in the bilayer sample with a small tunneling gap, while it is Ns=7 in the monolayer sample. The difference is interpreted to be due to the interlayer exchange interaction.In the next stage, we measured the magnetoresistance of bilayer QH effects at the fractional filling factor ν=2/3 by changing the total electron density and the density difference between two layers. Three different QH states were separated by two types of phase transition : One is the spin transition and the other is the pseudospin transition. In addition, two different hystereses were detected, one of which is specific to bilayer systems. The phase transitions and the hystereses are described well by a composite fermion model extended to a bilayer system.

首次在朗道能级填充因子ν=2的双层量子霍尔态和ν=1的单层量子霍尔态中测量并比较了Skyrmion激发。观察到的翻转自旋的数量，Ns，在具有大的隧道间隙的双层样品中为14，并且在具有小的隧道间隙的双层样品中为Ns=7，而在单层样品中为Ns=7。在下一阶段中，我们通过改变双层QH效应的总电子密度和两层之间的密度差，测量了分数填充因子ν=2/3时双层QH效应的磁电阻。三个不同的QH态被两种类型的相变分开：一种是自旋相变，另一种是赝自旋相变。此外，还检测到两种不同的荧光素酶，其中一种对双层系统具有特异性。用扩展到双层系统的复合费米子模型很好地描述了相变和相变。

项目成果

Z.F.Ezawa: "Interlayer exchange interactions, SU(4) soft waves, and skyrmions in bilayer quantum Hall ferromagnets"Physical Review B. 65. 75311-75321 (2002)

Z.F.Ezawa：“双层量子霍尔铁磁体中的层间交换相互作用、SU(4) 软波和斯格明子”物理评论 B. 65. 75311-75321 (2002)

A.Sawada: "Bilayer v=2 Quantum Hall State in Parallel High Magnetic Field"Physica E. 6・1-4. 615-618 (2000)

A.Sawada：“平行强磁场中的双层 v=2 量子霍尔态”Physica E. 6・1-4 (2000)。

N.Kumada: "Preferred number of flipped spins in Skyrme excitation"Physica B. 298. 169-172 (2001)

N.Kumada：“Skyrme 激发中翻转自旋的首选数量”Physica B. 298. 169-172 (2001)

江澤潤一: "2層量子ホール系における層間コヒーレント現象"日本物理学会誌. 56. 334-338 (2001)

Junichi Ezawa：“两层量子霍尔系统中的层间相干现象”日本物理学会杂志 56. 334-338 (2001)。

N.Kumada: "Various phase transitions in ν=2/3 bilayer quantum Hall states"Physica E.

N.Kumada：“ν=2/3 双层量子霍尔态中的各种相变”Physica E.