Interlayer Coherence in Bilayer Quantum Hall States

双层量子霍尔态的层间相干性

• 批准号: 10203201
• 负责人: SAWADA Anju
• 金额: $ 5.63万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research on Priority Areas (B)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10203201/
• 关键词: Quantm Hall Effect; Composite Boson; Activation Energy; Interlayer Coherence; Bose Condensation; Skyrmion; Pseudospin; Spin; ホールプラトー; 層間コヒーレント; ガリウム砒素; ホールプラントー

The activation energy was measured in the bilayer quantum Hall (QH) state at filling factor ν = 2 and 1, by changing the total electron density and the density ratio in the two quantutn wells. The ν = 1 state is found stable over all measured range of the density difference. The ν = 2 state, on the other hand, shows a phase transition between these two types of the states as the electron density is changed. The ν = 1 state is a "coherent" state stabilarized by the strong interlayer Coulomb interaction. The ν = 2 state shows a phase transition from the compound state to the "coherent" state as the interlayer Coulomb interaction becomes dominant. The appearance of such ν = 2 "coherent" state is a consequence of the spin degree of freedom in the bilayer QH state.We have measured the activation energy of the ν = 2 QH state at the balanced point (n_f = n_b) and the ν = 1 QH state at the monolayer point (n_f ≠ 0, n_b = 0) by tilting the samples. Skyrmion excitations were measured and compared for the flrst time in the 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, N_<spin>, is 14 in the bilayer sample with a large tunnelling gap, and N_<spin> = 7 in the bilayer sample with a small tunnelling gap, while it is N_<spin> = 7 in the monolayer sample. The difference is interpreted to be due to the interlayer exchange interaction.

通过改变两个量子威尔斯阱中的总电子密度和密度比，测量了填充因子ν = 2和1时双层量子霍尔（QH）态的激活能。发现ν = 1态在密度差的所有测量范围内都是稳定的。另一方面，当电子密度改变时，ν = 2状态显示出这两种状态之间的相变。ν = 1态是一个“相干”态，它被层间强库仑相互作用稳定化。当层间库仑相互作用占主导地位时，ν = 2态显示出从复合态到“相干”态的相变。我们用倾斜样品的方法测量了在平衡点（n_f = n_B）和单层点（n_f = 0，n_B = 0）的ν = 2 QH态和ν = 1 QH态的激活能。首次测量并比较了朗道能级填充因子ν = 2时QH态和ν = 1时单层QH态的Skyrmion激发。在<spin>具有大隧道隙的双层样品中观察到的翻转自旋数N = 14，<spin>在具有小隧道隙的双层样品中观察到的翻转自旋数N = 7，而<spin>在单层样品中观察到的翻转自旋数N = 7。这种差异被解释为是由于层间交换相互作用。

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