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

• Main Authors: Ji, Zhurun, Park, Heonjoon, Barber, Mark E, Hu, Chaowei, Watanabe, Kenji, Taniguchi, Takashi, Chu, Jiun-Haw, Xu, Xiaodong, Shen, Zhi-xun
• Format: Journal Article
• Language: English
• Published: 10-04-2024
• Subjects: Physics - Mesoscale and Nanoscale Physics; Physics - Strongly Correlated Electrons
• DOI: 10.48550/arxiv.2404.07157

Fractional quantum Hall effect (FQHE) is a prime 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 analog of FQHE 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 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 due
to experimental challenges. Here we report the imaging of FCI edge states in
twisted MoTe2 by employing a newly developed modality of 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 bulk-boundary correspondence. We also
observe the evolution of edge states across the topological phase transition
from an incompressible Chern insulator state to a metal and finally to a
putative charge ordered insulating state as a function of interlayer electric
field. The local measurement further reveals tantalizing prospects of
neighboring domains with different fractional orders. These findings pave the
way for research into topologically protected 1D interfaces between various
anyonic states at zero magnetic field, such as topological entanglement
entropy, Halperin-Laughlin interfaces, and the creation of non-abelian anyons.