Observation of fractional Chern insulators in a van der Waals heterostructure
Observation of fractional Chern insulators in a van der Waals heterostructure
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DOI：
10.1126/science.aan8458
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发表时间：
2018-04-06
期刊：
影响因子：
56.9
通讯作者：
Young, Andrea F.
中科院分区：
文献类型：
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作者：
Spanton, Eric M.;Zibrov, Alexander A.;Young, Andrea F.
拓扑有序相的特征是长程量子纠缠和分数统计，而不是对称破缺。首先在分数填充连续体朗道水平上观察到，自此以后，拓扑有序被提出更普遍地出现在拓扑非平凡陈氏带的分数填充中。本文报道了在双层石墨烯-六方氮化硼异质结构中，由于磁场和超晶格势的相互作用而引起的哈珀-霍夫施塔特带分数填充的间隙态的观察。我们在陈氏指数为C = -1、+/- 2和+/- 3的条带中观察到分数填充的相。这些相中的一些，在C = -1和C = 2带中，具有分数霍尔电导率的特征，也就是说，它们被称为分数陈氏绝缘体，并构成了超越朗道能级的拓扑秩序的一个例子。
Topologically ordered phases are characterized by long-range quantum entanglement and fractional statistics rather than by symmetry breaking. First observed in a fractionally filled continuum Landau level, topological order has since been proposed to arise more generally at fractional fillings of topologically nontrivial Chern bands. Here we report the observation of gapped states at fractional fillings of Harper-Hofstadter bands arising from the interplay of a magnetic field and a superlattice potential in a bilayer graphene-hexagonal boron nitride heterostructure. We observed phases at fractional filling of bands with Chern indices C = -1, +/- 2, and +/- 3. Some of these phases, in C = -1 and C = 2 bands, are characterized by fractional Hall conductance-that is, they are known as fractional Chern insulators and constitute an example of topological order beyond Landau levels.