Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice
Name
1905.06535.pdf
Description
Submitted version
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956.99 KB
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Checksum (MD5)
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Author(s)
Chen, Guorui
Sharpe, Aaron L
Fox, Eli J
Zhang, Ya-Hui
Wang, Shaoxin
Jiang, Lili
Lyu, Bosai
Li, Hongyuan
Watanabe, Kenji
Taniguchi, Takashi
Date Issued
2020
Journal
Nature
Publisher
Springer Science and Business Media LLC
Version
Original manuscript
Abstract
Studies on two-dimensional electron systems in a strong magnetic field first
revealed the quantum Hall (QH) effect, a topological state of matter featuring
a finite Chern number (C) and chiral edge states. Haldane later theorized that
Chern insulators with integer QH effects could appear in lattice models with
complex hopping parameters even at zero magnetic field. The ABC-trilayer
graphene/hexagonal boron nitride (TLG/hBN) moir\'e superlattice provides an
attractive platform to explore Chern insulators because it features nearly flat
moir\'e minibands with a valley-dependent electrically tunable Chern number.
Here we report the experimental observation of a correlated Chern insulator in
a TLG/hBN moir\'e superlattice. We show that reversing the direction of the
applied vertical electric field switches TLG/hBN's moir\'e minibands between
zero and finite Chern numbers, as revealed by dramatic changes in
magneto-transport behavior. For topological hole minibands tuned to have a
finite Chern number, we focus on 1/4 filling, corresponding to one hole per
moir\'e unit cell. The Hall resistance is well quantized at h/2e2, i.e. C = 2,
for |B| > 0.4 T. The correlated Chern insulator is ferromagnetic, exhibiting
significant magnetic hysteresis and a large anomalous Hall signal at zero
magnetic field. Our discovery of a C = 2 Chern insulator at zero magnetic field
should open up exciting opportunities for discovering novel correlated
topological states, possibly with novel topological excitations, in nearly flat
and topologically nontrivial moir\'e minibands.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1038/S41586-020-2049-7
