Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice
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 latti...
| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Springer Science and Business Media LLC
2021
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| Online Access: | https://hdl.handle.net/1721.1/132577 |
| _version_ | 1826205840984506368 |
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| author | Chen, Guorui Sharpe, Aaron L Fox, Eli J Zhang, Ya-Hui Wang, Shaoxin Jiang, Lili Lyu, Bosai Li, Hongyuan Watanabe, Kenji Taniguchi, Takashi Shi, Zhiwen Senthil, T Goldhaber-Gordon, David Zhang, Yuanbo Wang, Feng |
| author_facet | Chen, Guorui Sharpe, Aaron L Fox, Eli J Zhang, Ya-Hui Wang, Shaoxin Jiang, Lili Lyu, Bosai Li, Hongyuan Watanabe, Kenji Taniguchi, Takashi Shi, Zhiwen Senthil, T Goldhaber-Gordon, David Zhang, Yuanbo Wang, Feng |
| author_sort | Chen, Guorui |
| collection | MIT |
| description | 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. |
| first_indexed | 2024-09-23T13:19:57Z |
| format | Article |
| id | mit-1721.1/132577 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T13:19:57Z |
| publishDate | 2021 |
| publisher | Springer Science and Business Media LLC |
| record_format | dspace |
| spelling | mit-1721.1/1325772021-09-21T03:30:22Z Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice Chen, Guorui Sharpe, Aaron L Fox, Eli J Zhang, Ya-Hui Wang, Shaoxin Jiang, Lili Lyu, Bosai Li, Hongyuan Watanabe, Kenji Taniguchi, Takashi Shi, Zhiwen Senthil, T Goldhaber-Gordon, David Zhang, Yuanbo Wang, Feng 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. 2021-09-20T18:23:09Z 2021-09-20T18:23:09Z 2020-11-10T15:47:27Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/132577 en 10.1038/S41586-020-2049-7 Nature Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf Springer Science and Business Media LLC arXiv |
| spellingShingle | Chen, Guorui Sharpe, Aaron L Fox, Eli J Zhang, Ya-Hui Wang, Shaoxin Jiang, Lili Lyu, Bosai Li, Hongyuan Watanabe, Kenji Taniguchi, Takashi Shi, Zhiwen Senthil, T Goldhaber-Gordon, David Zhang, Yuanbo Wang, Feng Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice |
| title | Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice |
| title_full | Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice |
| title_fullStr | Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice |
| title_full_unstemmed | Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice |
| title_short | Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice |
| title_sort | tunable correlated chern insulator and ferromagnetism in a moire superlattice |
| url | https://hdl.handle.net/1721.1/132577 |
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