Unconventional Sequence of Fractional Quantum Hall States in Suspended Graphene
Unconventional Sequence of Fractional Quantum Hall States in Suspended Graphene
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DOI：
10.1126/science.1224784
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发表时间：
2012-09-07
期刊：
影响因子：
56.9
通讯作者：
Yacoby, Amir
中科院分区：
文献类型：
--
作者：
Feldman, Benjamin E.;Krauss, Benjamin;Yacoby, Amir
石墨烯由于其无质量的手性电荷载流子以及其自旋和谷自由度产生的四重简并性，为研究多体效应提供了丰富的平台。我们使用扫描单电子晶体管来测量悬浮石墨烯的局部电子可压缩性，并且观察到不可压缩分数量子霍尔态的不寻常模式，该模式遵循填充因子 nu = 0 和 1 之间的标准复合费米子序列，但仅涉及 nu = 1 和 2 之间的偶数分子分数。我们通过提取相应的能隙作为磁场的函数，进一步研究了这种令人惊讶的层次结构。分数量子霍尔态的序列和相对强度提供了对电子相关性和石墨烯固有对称性之间相互作用的深入了解。
Graphene provides a rich platform to study many-body effects, owing to its massless chiral charge carriers and the fourfold degeneracy arising from their spin and valley degrees of freedom. We use a scanning single-electron transistor to measure the local electronic compressibility of suspended graphene, and we observed an unusual pattern of incompressible fractional quantum Hall states that follows the standard composite fermion sequence between filling factors nu = 0 and 1 but involves only even-numerator fractions between nu = 1 and 2. We further investigated this surprising hierarchy by extracting the corresponding energy gaps as a function of the magnetic field. The sequence and relative strengths of the fractional quantum Hall states provide insight into the interplay between electronic correlations and the inherent symmetries of graphene.