该研究团队报道了在超高质量GaAs二维空穴系统中，在v= 3/10、3/8和3/4处观察到的偶数分母FQHS。这些状态表现为纵向电阻的深度最小值和量子化霍尔平台的形成。值得注意的是，当CFs朗道能级而不是电子或空穴朗道能级被半填满时，这些态可以解释为CFs的偶分子FQHS，产生于高阶CFs的配对。该研究结果证实，在朗道能级混合显著的空穴体系中，CFs之间的相互作用增强。更普遍地说，CFs的配对是偶分子FQHS的有效机制。此外，该研究还建议使用非阿贝尔任意子实现FQHS。
据悉，1982年分数量子霍尔态（FQHS）的发现开启了多体凝聚态物理研究的新时代。在众多的FQHS中，那些在偶分母朗道能级填充因子下观察到的FQHS特别有趣，因为它们可能包含服从非阿贝尔统计的准粒子，并且在拓扑量子计算中具有潜在的用途。然而，偶分母FQHS是稀缺的，并且主要是当激发电子朗道能级半填满时，在低无序二维（2D）系统中观察到。以填充因子v= 5/2时的FQHS为例，它被认为是通量-粒子复合费米子（CFs）的Bardeen-Cooper-Schrieffer型配对态。
附：英文原文
Title: Next-generation even-denominator fractional quantum Hall states of interacting composite fermions
Author: Wang, Chengyu, Gupta, Adbhut, Madathil, Pranav T., Singh, Siddharth K., Chung, Yoon Jang, Pfeiffer, Loren N., Baldwin, Kirk W., Shayegan, Mansour
Issue&Volume: 2023-12-19
Abstract: The discovery of the fractional quantum Hall state (FQHS) in 1982 ushered a new era of research in many-body condensed matter physics. Among the numerous FQHSs, those observed at even-denominator Landau level filling factors are of particular interest as they may host quasiparticles obeying non-Abelian statistics and be of potential use in topological quantum computing. The even-denominator FQHSs, however, are scarce and have been observed predominantly in low-disorder two-dimensional (2D) systems when an excited electron Landau level is half filled. An example is the well-studied FQHS at filling factor v= 5/2 which is believed to be a Bardeen-Cooper-Schrieffer-type, paired state of flux-particle composite fermions (CFs). Here, we report the observation of even-denominator FQHSs at v= 3/10, 3/8, and 3/4 in the lowest Landau level of an ultrahigh-quality GaAs 2D hole system, evinced by deep minima in longitudinal resistance and developing quantized Hall plateaus. Quite remarkably, these states can be interpreted as even-denominator FQHSs of CFs, emerging from pairing of higher-order CFs when a CF Landau level, rather than an electron or a hole Landau level, is half-filled. Our results affirm enhanced interaction between CFs in a hole system with significant Landau level mixing and, more generally, the pairing of CFs as a valid mechanism for even-denominator FQHSs, and suggest the realization of FQHSs with non-Abelian anyons.
DOI: 10.1073/pnas.2314212120
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2314212120