Geometric resonance of four-flux composite fermions
Geometric resonance of four-flux composite fermions
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DOI：
10.1103/physrevb.100.041112
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发表时间：
2019-07
影响因子：
3.7
通讯作者：
M. S. Hossain;M. Ma;M. A. Mueed;D. Kamburov;L. Pfeiffer;K. West;K. Baldwin;R. Winkler;M. Shayegan
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文献类型：
--
作者：
M. S. Hossain;M. Ma;M. A. Mueed;D. Kamburov;L. Pfeiffer;K. West;K. Baldwin;R. Winkler;M. Shayegan
暴露在强垂直磁场中的二维相互作用电子会产生新出现的奇异准粒子，其现象学上与电子不同。具体来说，电子与偶数个通量量子结合，并转化为复合费米子（CF）。除了为分数量子霍尔态提供直观的解释外，CF 还具有类似费米液体的特性，包括明确定义的费米海，处于或接近偶分母朗道能级填充因子，例如 $\nu=1/2$ 或 $1/4$。在这里，我们通过几何共振实验直接探测$\nu=1/4$附近很少研究的四通量CF的费米海。这些数据揭示了一些独特的特征。与双磁通 CF 的情况不同，$\nu 1/4$ 的几何谐振电阻最小值的磁场位置相对于 $\nu=1/4$ 的位置对称。然而，当施加面内磁场时，最小值位置变得不对称，这意味着 CF 费米海各向异性 $\nu 1/4$ 存在神秘的不对称性。这种不对称性与双通量 CF 形成鲜明对比，表明 $\nu=1/4$ 两侧的四通量 CF 具有非常不同的有效质量，可能是因为小 $\nu$ 处的维格纳晶体形成很接近。
Two-dimensional interacting electrons exposed to strong perpendicular magnetic fields generate emergent, exotic quasiparticles phenomenologically distinct from electrons. Specifically, electrons bind with an even number of flux quanta, and transform into composite fermions (CFs). Besides providing an intuitive explanation for the fractional quantum Hall states, CFs also possess Fermi-liquid-like properties, including a well-defined Fermi sea, at and near even-denominator Landau level filling factors such as $\nu=1/2$ or $1/4$. Here, we directly probe the Fermi sea of the rarely studied four-flux CFs near $\nu=1/4$ via geometric resonance experiments. The data reveal some unique characteristics. Unlike in the case of two-flux CFs, the magnetic field positions of the geometric resonance resistance minima for $\nu 1/4$ are symmetric with respect to the position of $\nu=1/4$. However, when an in-plane magnetic field is applied, the minima positions become asymmetric, implying a mysterious asymmetry in the CF Fermi sea anisotropy for $\nu 1/4$. This asymmetry, which is in stark contrast to the two-flux CFs, suggests that the four-flux CFs on the two sides of $\nu=1/4$ have very different effective masses, possibly because of the proximity of the Wigner crystal formation at small $\nu$.