近日，美国斯坦福大学的Zhi-Xun Shen与华盛顿大学的Xiaodong Xu等人合作并取得一项新进展。他们对分数阶陈绝缘子中体边态进行了局部探测。相关研究成果已于2024年11月20日在国际权威学术期刊《自然》上发表。

本文报道了使用微波阻抗显微镜，对扭曲二碲化钼（t-MoTe2）中的分数量子陈绝缘体（FCI）边缘态进行成像的研究。通过调节载流子密度，研究人员观察到系统从金属态向FCI态演变，后者如体边对应原理所预期，表现出绝缘的体态和导电的边缘。

进一步分析表明，FCI边缘态具有复合性质。研究人员还观察了随层间电场变化时，边缘态在拓扑相变过程中的演变，并揭示了具有不同分数序的相邻区域所展现出的激动人心前景。

这些发现为零磁场下研究各种任意子态之间，受拓扑保护的一维界面铺平了道路，例如具有非零拓扑纠缠熵的带隙一维对称保护相、Halperin-Laughlin界面以及非阿贝尔任意子的产生。

据悉，分数量子霍尔效应是拓扑量子多体现象的一个关键实例，它源于强电子关联性、拓扑序和时间反演对称性破缺之间的相互作用。近期，人们在零磁场下观察到了分数量子霍尔效应的晶格类似物，证实了零场分数量子陈绝缘体（FCI）的存在。

尽管如此，体边对应——即具有导电边缘的绝缘体态的FCI的一个标志性特征——尚未被直接观察到。事实上，由于实验上的挑战，这种对应在任何分数态系统中都尚未实现可视化。

附：英文原文

Title: Local probe of bulk and edge states in a fractional Chern insulator

Author: Ji, Zhurun, Park, Heonjoon, Barber, Mark E., Hu, Chaowei, Watanabe, Kenji, Taniguchi, Takashi, Chu, Jiun-Haw, Xu, Xiaodong, Shen, Zhi-Xun

Issue&Volume: 2024-11-20

Abstract: The fractional quantum Hall effect is a key example of topological quantum many-body phenomena, arising from the interplay between strong electron correlation, topological order and time-reversal symmetry breaking. Recently, a lattice analogue of the fractional quantum Hall effect at zero magnetic field has been observed, confirming the existence of a zero-field fractional Chern insulator (FCI). Despite this, the bulk–edge correspondence—a hallmark of a FCI featuring an insulating bulk with conductive edges—has not been directly observed. In fact, this correspondence has not been visualized in any system for fractional states owing to experimental challenges. Here we report the imaging of FCI edge states in twisted MoTe2 (t-MoTe2) using microwave impedance microscopy. By tuning the carrier density, we observe the system evolving between metallic and FCI states, the latter of which exhibits insulating bulk and conductive edges, as expected from the bulk–boundary correspondence. Further analysis suggests the composite nature of the FCI edge states. We also observe the evolution of edge states across the topological phase transition as a function of interlayer electric field and reveal exciting prospects of neighbouring domains with different fractional orders. These findings pave the way for research into topologically protected one-dimensional interfaces between various anyonic states at zero magnetic field, such as gapped one-dimensional symmetry-protected phases with non-zero topological entanglement entropy, Halperin–Laughlin interfaces and the creation of non-abelian anyons.

DOI: 10.1038/s41586-024-08092-7

Source: https://www.nature.com/articles/s41586-024-08092-7