Composite Fermions waltz to the tune of a Wigner crystal
Composite Fermions waltz to the tune of a Wigner crystal
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复合费米子随着维格纳晶体的曲调跳出华尔兹
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
K. Baldwin
中科院分区：
文献类型：
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作者：
Yang Liu;H. Deng;M. Shayegan;L. Pfeiffer;K. West;K. Baldwin
当相互作用的二维（2D）电子集合的动能在非常高的磁场下被淬灭，使得库仑斥力占主导地位时，预计电子将凝聚成有序阵列，形成量子维格纳晶体（WC）。虽然这种奇异态长期以来一直被怀疑存在于朗道能级非常低（ν << 1）的高迁移率二维电子系统中，但它的直接观测一直难以捉摸。本文介绍了一种直接探测磁场感应WC的新技术和实验结果。我们测量了在高磁场下具有不等层密度的双层电子系统的磁电阻。其中一层密度很低，处于WC区（ν << 1），而另一层（“探针”）在ν = 1/2附近，拥有大量的复合费米子，这是一种准粒子，通过将两个通量量子附加到每个相互作用的电子上而形成。复合费米子感受到另一层WC的周期电势，当它们的回旋轨道环绕一定整数的WC晶格点时，它们的磁电阻达到最大值。极大值的位置表明WC具有三角形晶格，并可直接测量其晶格常数。我们的结果提供了一个引人注目的例子，说明如何使用另一个多体态的同样奇异的准粒子来探测二维电子的奇异多体态。
When the kinetic energy of a collection of interacting two-dimensional (2D) electrons is quenched at very high magnetic fields so that the Coulomb repulsion dominates, the electrons are expected to condense into an ordered array, forming a quantum Wigner crystal (WC). Although this exotic state has long been suspected in high-mobility 2D electron systems at very low Landau level fillings (ν << 1), its direct observation has been elusive. Here we present a new technique and experimental results that directly probe the magnetic-field-induced WC. We measure the magneto-resistance of a bilayer electron system with unequal layer densities at high magnetic fields. One layer has a very low density and is in the WC regime (ν << 1), while the other (”probe”) layer is near ν = 1/2 and hosts a sea of composite fermions, quasi-particles formed by attaching two flux-quanta to each interacting electron. The composite fermions feel the periodic electric potential of the WC in the other layer and exhibit magneto-resistance maxima whenever their cyclotron orbit encircles certain integer number of the WC lattice points. The positions of the maxima reveal that the WC has a triangular lattice and yield a direct measure of its lattice constant. Our results provide a striking example of how one can probe an exotic many-body state of 2D electrons using equally exotic quasi-particles of another many-body state.