Hatke A T, Liu Y, Engel L W, Shayegan M, Pfeiffer L N, West K W, Baldwin K W
National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA.
Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
Nat Commun. 2015 May 7;6:7071. doi: 10.1038/ncomms8071.
At the low Landau filling factor termination of the fractional quantum Hall effect series, two-dimensional electron systems exhibit an insulating phase that is understood as a form of pinned Wigner solid. Here we use microwave spectroscopy to probe the transition to the insulator for a wide quantum well sample that can support single-layer or bilayer states depending on its overall carrier density. We find that the insulator exhibits a resonance which is characteristic of a bilayer solid. The resonance also reveals a pair of transitions within the solid, which are not accessible to dc transport measurements. As density is biased deeper into the bilayer solid regime, the resonance grows in specific intensity, and the transitions within the insulator disappear. These behaviours are suggestive of a picture of the insulating phase as an emulsion of liquid and solid components.
在分数量子霍尔效应系列的低朗道填充因子终止处，二维电子系统呈现出一种绝缘相，这种绝缘相被理解为一种钉扎维格纳固体的形式。在此，我们使用微波光谱法来探测一个宽量子阱样品向绝缘体的转变，该样品根据其整体载流子密度可支持单层或双层状态。我们发现，该绝缘体呈现出一种双层固体特有的共振。这种共振还揭示了固体内部的一对转变，这是直流输运测量无法探测到的。随着密度进一步偏向双层固体区域，共振的特定强度增加，并且绝缘体内部的转变消失。这些行为暗示了绝缘相是液体和固体成分的乳状液的图像。
