干涉测量揭示石墨烯中的自旋单分数量子霍尔边缘态

中文摘要 AI 辅助

自旋单分数量子霍尔（FQH）相的边缘模式是多分量拓扑序和SU(2)自旋对称性的体现，典型例子是填充因子ν=2/3的自旋非极化态，其边缘预计存在空间共存但反向传播的电荷模式与中性自旋模式。尽管已有研究，但由于FQH边缘输运中自旋难以分辨，该边缘的自旋相干性、自旋-电荷分离等性质仍未明确。本文通过p-n结将目标FQH态与极性相反的探测整数量子霍尔（QH）态耦合，开发了一种自旋敏感的石墨烯FQH边缘探测方法；当目标与探测边缘通道携带相同自旋时，界面会形成阿哈罗诺夫-玻姆（AB）干涉仪。我们通过自旋依赖干涉，确定ν=2/3态在低磁场下为自旋非极化边缘、高磁场下为自旋极化边缘；非极化边缘上，自旋-电荷分离与复合产生了由反向自旋双电子形成的新型多粒子AB干涉，表现出自旋交换特征。本研究确立了边缘输运作为自旋单态拓扑序的探测手段，对石墨烯-超导体混合结构中的parafermion平台具有重要意义。

英文摘要

The edge modes of spin-singlet fractional quantum Hall (FQH) phases are manifestations of multicomponent topological order and SU(2) spin symmetry. An archetype is the spin-unpolarized state at $ν$=2/3, whose edge is expected to host spatially coexisting yet counter-propagating charge and neutral spin modes. Despite efforts, its edge properties, including spin coherence and spin-charge separation, have remained elusive owing to the difficulty of resolving spins in FQH edge transport. Here, we develop a spin-sensitive probe of graphene FQH edges by using a p-n junction to interface a target FQH state with a probe integer quantum Hall (QH) state of opposite polarity. An Aharonov-Bohm (AB) interferometer forms along the interface, when the target and probe edge channels carry the same spin. We identify the spin-unpolarized and polarized edges of the $ν$=2/3 states at lower and higher magnetic fields, respectively, through spin-dependent interference. A novel multiparticle AB interference between two electrons of opposite spin emerges from spin-charge separation and recombination on the unpolarized edge, featuring a spin swap. Our results establish edge transport as a probe of spin-singlet topological orders, with implications for parafermion platforms in graphene-superconductor hybrids.

发表机构

• SPEC, CEA, CNRS, Université Paris-Saclay（SPEC, CEA, CNRS, 巴黎萨克雷大学）
• Department of Physics, Korea Advanced Institute of Science and Technology（韩国科学技术院物理系）
• Department of Physics, Birla Institute of Technology and Science, Pilani, Hyderabad Campus（比拉理工理工学院（皮拉尼海德拉巴校区）物理系）
• National Institute for Materials Science（物质材料研究机构）

机构由 AI 辅助整理，请以论文原文为准。