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Evidence of frustrated magnetic interactions in a Wigner–Mott insulator

Cornell Affiliated Author(s)


Yanhao Tang
Kaixiang Su
Lizhong Li
Yang Xu
Song Liu
Kenji Watanabe
Takashi Taniguchi
James Hone
Chao-Ming Jian
Cenke Xu
Kin Mak
Jie Shan


Electrons in two-dimensional semiconductor moiré materials are more delocalized around the lattice sites than those in conventional solids1,2. The non-local contributions to the magnetic interactions can therefore be as important as the Anderson superexchange3, which makes the materials a unique platform to study the effects of competing magnetic interactions3,4. Here we report evidence of strongly frustrated magnetic interactions in a Wigner–Mott insulator at a two-thirds (2/3) filling of the moiré lattice in angle-aligned WSe2/WS2 bilayers. Magneto-optical measurements show that the net exchange interaction is antiferromagnetic for filling factors below 1 with a strong suppression at a 2/3 filling. The suppression is lifted on screening of the long-range Coulomb interactions and melting of the Wigner–Mott insulators by a nearby metallic gate. The results can be qualitatively captured by a honeycomb-lattice spin model with an antiferromagnetic nearest-neighbour coupling and a ferromagnetic second-neighbour coupling. Our study establishes semiconductor moiré materials as a model system for lattice-spin physics and frustrated magnetism5. © 2023, The Author(s), under exclusive licence to Springer Nature Limited.

Date Published


Nature Nanotechnology





Number of Pages





Group (Lab)

Chao-Ming Jian Group
Jie Shan Group
Kin Fai Mak Group

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