Imaging orbital ferromagnetism in a moiré Chern insulator

Tschirhart, C. L.; Serlin, M.; Polshyn, Hryhoriy; Shragai, A.; Xia, Z.; Zhu, J.; Zhang, Y.; Watanabe, K.; Taniguchi, T.; Huber, M. E.; Young, A. F.

Imaging orbital ferromagnetism in a moiré Chern insulator

Tschirhart CL, Serlin M, Polshyn H, Shragai A, Xia Z, Zhu J, Zhang Y, Watanabe K, Taniguchi T, Huber ME, Young AF. 2021. Imaging orbital ferromagnetism in a moiré Chern insulator. Science. 372(6548), 1323–1327.

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https://arxiv.org/abs/2006.08053 [Preprint]

DOI

10.1126/science.abd3190

Journal Article | Published | English

Scopus indexed

Author

Tschirhart, C. L.; Serlin, M.; Polshyn, Hryhoriy^ISTA ; Shragai, A.; Xia, Z.; Zhu, J.; Zhang, Y.; Watanabe, K.; Taniguchi, T.; Huber, M. E.; Young, A. F.

Abstract

Electrons in moiré flat band systems can spontaneously break time-reversal symmetry, giving rise to a quantized anomalous Hall effect. In this study, we use a superconducting quantum interference device to image stray magnetic fields in twisted bilayer graphene aligned to hexagonal boron nitride. We find a magnetization of several Bohr magnetons per charge carrier, demonstrating that the magnetism is primarily orbital in nature. Our measurements reveal a large change in the magnetization as the chemical potential is swept across the quantum anomalous Hall gap, consistent with the expected contribution of chiral edge states to the magnetization of an orbital Chern insulator. Mapping the spatial evolution of field-driven magnetic reversal, we find a series of reproducible micrometer-scale domains pinned to structural disorder.

Keywords

multidisciplinary

Publishing Year

2021

Date Published

2021-05-27

Journal Title

Science

Publisher

American Association for the Advancement of Science

Acknowledgement

We thank A. H. Macdonald, J. Zhu, M. Zaletel, and D. Xiao for discussions of the results and E. Lachman for comments on the manuscript. Funding: The work was primarily funded by the US Department of Energy under DE-SC0020043, with additional support for instrumentation development supported by the Army Research Office under grant W911NF-16-1-0361. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by MEXT, Japan, grant JPMXP0112101001; JSPS KAKENHI grant JP20H00354 and CREST grant JPMJCR15F3, JST. C.L.T. acknowledges support from the Hertz Foundation and from the National Science Foundation Graduate Research Fellowship Program under grant 1650114. This project is funded in part by the Gordon and Betty Moore Foundation’s EPiQS Initiative, grant GBMF9471 to A.F.Y.

Volume

372

Issue

6548

Page

1323-1327

ISSN

0036-8075

eISSN

1095-9203

IST-REx-ID

10616

Cite this

Tschirhart CL, Serlin M, Polshyn H, et al. Imaging orbital ferromagnetism in a moiré Chern insulator. Science. 2021;372(6548):1323-1327. doi:10.1126/science.abd3190

Tschirhart, C. L., Serlin, M., Polshyn, H., Shragai, A., Xia, Z., Zhu, J., … Young, A. F. (2021). Imaging orbital ferromagnetism in a moiré Chern insulator. Science. American Association for the Advancement of Science. https://doi.org/10.1126/science.abd3190

Tschirhart, C. L., M. Serlin, Hryhoriy Polshyn, A. Shragai, Z. Xia, J. Zhu, Y. Zhang, et al. “Imaging Orbital Ferromagnetism in a Moiré Chern Insulator.” Science. American Association for the Advancement of Science, 2021. https://doi.org/10.1126/science.abd3190.

C. L. Tschirhart et al., “Imaging orbital ferromagnetism in a moiré Chern insulator,” Science, vol. 372, no. 6548. American Association for the Advancement of Science, pp. 1323–1327, 2021.

Tschirhart, C. L., et al. “Imaging Orbital Ferromagnetism in a Moiré Chern Insulator.” Science, vol. 372, no. 6548, American Association for the Advancement of Science, 2021, pp. 1323–27, doi:10.1126/science.abd3190.

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