arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1907.07563cond-mat.str-elcond-mat.mes-hall
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四磁通复合费米子的几何共振

Geometric Resonance of Four-Flux Composite Fermions

Md. Shafayat Hossain, Meng K. Ma, M. A. Mueed, D. Kamburov, L. N. Pfeiffer, K. W. West, K. W. Baldwin, R. Winkler, M. Shayegan

摘要:

二维相互作用的电子暴露在强垂直磁场中,产生出与电子不同的奇异准粒子。具体地说,电子与偶数个通量量子结合,并转化为复合费米子(CF)。除了对分数量子霍尔态提供直观的解释外,CF还具有费米液体的性质,包括定义明确的费米海,在和接近偶数分母朗道能级填充因子,如$ν=1/2$或$1/4$。在这里,我们通过几何共振实验直接探测了$ν=1/4$附近很少研究的四通量CFs的费米海。数据显示了一些独特的特征。与双通量CF的情况不同,$ν<1/4$和$ν>1/4$的几何谐振电阻最小值的磁场位置相对于$ν=1/4$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$ν<1/4$和$ν>1/4$的CF费米海各向异性中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$ν=1/4$两侧的四通量CF具有非常不同的有效质量,这可能是因为在小$ν$时维格纳晶体形成的接近性。

英文摘要:

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 $ν=1/2$ or $1/4$. Here, we directly probe the Fermi sea of the rarely studied four-flux CFs near $ν=1/4$ 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 $ν<1/4$ and $ν>1/4$ are symmetric with respect to the position of $ν=1/4$. 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 $ν<1/4$ and $ν>1/4$. This asymmetry, which is in stark contrast to the two-flux CFs, suggests that the four-flux CFs on the two sides of $ν=1/4$ have very different effective masses, possibly because of the proximity of the Wigner crystal formation at small $ν$.

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