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arXiv 1005.3879cond-mat.mes-hall
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分数量子霍尔效应单粒子谱中的反常结构

Anomalous structure in the single particle spectrum of the fractional quantum Hall effect

O. E. Dial, R. C. Ashoori, L. N. Pfeiffer, K. W. West

摘要:

二维电子系统(2DES)是研究相互作用粒子物理的独特实验室。应用一个大的磁场产生大量简并的量子能级,称为朗道能级。在朗道能级内,电子的动能被抑制,电子-电子相互作用设定唯一的能量尺度。库仑相互作用打破了朗道能级的简并性,并且可以使电子有序地进入复杂的基态。在这个系统的高能量单粒子谱,我们观察到突出的和意想不到的结构,扩展到广泛的朗道能级填充分数。只有当2DES被冷却到非常低的温度时,这种结构才会出现,这表明它是由微妙的基态相关性引起的。我们通过改变电子密度和外加磁场来表征这种结构。我们提出了两种可能的模型来理解这些观察。某些特征的能量在性质上与复合费米子的预期一致,复合费米子已被证明对解释这一领域的其他实验是有效的。与此同时,一个简单的模型,电子局域在有序的晶格位置也产生类似的结构在实验中观察到的。这些模型都不足以解释整个密度测量范围内的观测结果。在一个被彻底研究的系统的单粒子谱中发现了这个意想不到的突出结构,这表明2DES存在尚未被理解的核心特征。

英文摘要:

The two-dimensional electron system (2DES) is a unique laboratory for the physics of interacting particles. Application of a large magnetic field produces massively degenerate quantum levels known as Landau levels. Within a Landau level the kinetic energy of the electrons is suppressed, and electron-electron interactions set the only energy scale. Coulomb interactions break the degeneracy of the Landau levels and can cause the electrons to order into complex ground states. In the high energy single particle spectrum of this system, we observe salient and unexpected structure that extends across a wide range of Landau level filling fractions. The structure appears only when the 2DES is cooled to very low temperature, indicating that it arises from delicate ground state correlations. We characterize this structure by its evolution with changing electron density and applied magnetic field. We present two possible models for understanding these observations. Some of the energies of the features agree qualitatively with what might be expected for composite Fermions, which have proven effective for interpreting other experiments in this regime. At the same time, a simple model with electrons localized on ordered lattice sites also generates structure similar to those observed in the experiment. Neither of these models alone is sufficient to explain the observations across the entire range of densities measured. The discovery of this unexpected prominent structure in the single particle spectrum of an otherwise thoroughly studied system suggests that there exist core features of the 2DES that have yet to be understood.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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