Coexisting ferromagnetic-antiferromagnetic state in twisted bilayer CrI3

Yang Xu; Ariana Ray; Yu-Tsun Shao; Shengwei Jiang; Kihong Lee; Daniel Weber; Joshua E Goldberger; Kenji Watanabe; Takashi Taniguchi; David A Muller; Kin Fai Mak; Jie Shan

doi:10.1038/s41565-021-01014-y

Coexisting ferromagnetic-antiferromagnetic state in twisted bilayer CrI₃

Nat Nanotechnol. 2022 Feb;17(2):143-147. doi: 10.1038/s41565-021-01014-y. Epub 2021 Nov 29.

Authors

Yang Xu^{1

2}, Ariana Ray³, Yu-Tsun Shao¹, Shengwei Jiang³, Kihong Lee³, Daniel Weber⁴, Joshua E Goldberger⁴, Kenji Watanabe⁵, Takashi Taniguchi⁶, David A Muller^{1

7}, Kin Fai Mak^{8

9

10}, Jie Shan^{11

12

13}

Affiliations

¹ School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
² Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
³ Department of Physics, Cornell University, Ithaca, NY, USA.
⁴ Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA.
⁵ Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan.
⁶ International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan.
⁷ Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.
⁸ School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA. kinfai.mak@cornell.edu.
⁹ Department of Physics, Cornell University, Ithaca, NY, USA. kinfai.mak@cornell.edu.
¹⁰ Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA. kinfai.mak@cornell.edu.
¹¹ School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA. jie.shan@cornell.edu.
¹² Department of Physics, Cornell University, Ithaca, NY, USA. jie.shan@cornell.edu.
¹³ Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA. jie.shan@cornell.edu.

PMID: 34845332
DOI: 10.1038/s41565-021-01014-y

Abstract

Moiré engineering^1-3 of van der Waals magnetic materials^4-9 can yield new magnetic ground states via competing interactions in moiré superlattices^10-13. Theory predicts a suite of interesting phenomena, including multiflavour magnetic states¹⁰, non-collinear magnetic states^10-13, moiré magnon bands and magnon networks¹⁴ in twisted bilayer magnetic crystals, but so far such non-trivial magnetic ground states have not emerged experimentally. Here, by utilizing the stacking-dependent interlayer exchange interactions in two-dimensional magnetic materials^15-18, we demonstrate a coexisting ferromagnetic (FM) and antiferromagnetic (AF) ground state in small-twist-angle CrI₃ bilayers. The FM-AF state transitions to a collinear FM ground state above a critical twist angle of about 3°. The coexisting FM and AF domains result from a competition between the interlayer AF coupling, which emerges in the monoclinic stacking regions of the moiré superlattice, and the energy cost for forming FM-AF domain walls. Our observations are consistent with the emergence of a non-collinear magnetic ground state with FM and AF domains on the moiré length scale^10-13. We further employ the doping dependence of the interlayer AF interaction to control the FM-AF state by electrically gating a bilayer sample. These experiments highlight the potential to create complex magnetic ground states in twisted bilayer magnetic crystals, and may find application in future gate-voltage-controllable high-density magnetic memory storage.