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arXiv 2610.22348cond-mat.mes-hallcond-mat.str-el
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极化ν=2/3分数量子(反常)霍尔异质结构中的 parafermion(准费米子)

Parafermions in polarized $ν=2/3$ Fractional Quantum (Anomalous) Hall Heterostructures

Max-Planck Institute for Solid State Research(马克斯·普朗克固体研究所);University of Luxembourg(卢森堡大学);Purdue University(普渡大学);University of Wisconsin-Madison(威斯康星大学麦迪逊分校)

Steffen Bollmann, Andreas Haller, Thomas L. Schmidt, Jukka I. Väyrynen, Elio J. König

AI总结:

该研究针对与超导体近邻耦合的自旋极化ν=2/3分数量子霍尔态边缘,通过玻色化和重整化群分析,揭示了干净系统和无序系统中Z₃准费米子零模的稳定机制。

摘要:

受二维量子材料中分数陈绝缘体的最新实验迹象启发,我们研究了在与超导体近邻耦合的自旋极化ν=2/3分数量子霍尔态边缘上实现Z₃准费米子零模(PZMs)的情况。与自旋非极化的Halperin态不同,极化ν=2/3边缘包含反向传播的电子和分数准空穴模式,产生大量相互竞争的隧穿与配对过程。我们聚焦于这些模式重组为退耦的电荷与中性区的不动点附近,其中中性区描述涌现的偶极自由度。利用玻色化和重整化群分析,我们确定了参数空间,在该空间中边缘间偶极相互作用使中性区打开能隙,以稳定一个主导隧穿通道和一个主导配对通道,从而在电荷区得到双正弦-戈登模型,其在畴壁处支持Z₃ PZMs。我们同时讨论了干净系统和无序系统:干净系统中,该机制需要对相互作用强度和范围有一定程度的控制;相比之下,无序可提供更通用的途径:两个边缘上短程、与边缘无关联的无序会抑制稳定准费米子模式所需的同时钉扎,而当两个边缘上的无序足够关联时(正如平滑无序势所预期的),承载PZMs的参数范围会扩大。

英文摘要:

Motivated by recent experimental signatures of fractional Chern insulators in 2D quantum materials, we investigate the realization of $\mathbb Z_3$ parafermion zero modes (PZMs) on edges of spin-polarized $ν=2/3$ fractional quantum Hall states which are proximitized by superconductors. Unlike the spin-unpolarized Halperin state, the polarized $ν=2/3$ edge contains counterpropagating electron and fractional quasihole modes, giving rise to a plethora of competing tunneling and pairing processes. We focus on the vicinity of the fixed point where these modes reorganize into decoupled charge and neutral sectors, with the neutral sector describing an emergent dipole degree of freedom. Using bosonization and renormalization group analysis, we lay out the parameter space in which the interedge dipole interactions gap the neutral sector to stabilize one dominant tunneling and one dominant pairing channel resulting in a double sine-Gordon model in the charge sector which supports $\mathbb{Z}_3$ PZMs at domain walls. We discuss both clean and disordered systems. In clean systems this mechanism requires a certain degree of control of the interaction strength and range. In contrast, disorder can provide a more generic route: While short-ranged, edge-uncorrelated disorder % on the two edges suppresses the simultaneous pinning required for stable parafermion modes, when the disorder on the two edges is sufficiently correlated, as expected for smooth disorder potentials, the parameter regime hosting PZMs increases.

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