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arXiv · 2207.02312

Realization of the Haldane Chern insulator in a moir\'e lattice

Wenjin Zhao·Kaifei Kang·Lizhong Li·Charles Tschirhart·Evgeny Redekop·Kenji Watanabe·Takashi Taniguchi·Andrea Young·Jie Shan·Kin Fai Mak
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Abstract

The Chern insulator displays a quantized Hall effect without Landau levels. In a landmark paper in 1988, Haldane showed that a Chern insulator could be realized through complex next-nearest-neighbor hopping in a honeycomb lattice. Despite its profound impact on the field of topological physics and recent implementation in cold-atom experiments, the Haldane model has remained elusive in solid-state materials. Here, we report the experimental realization of a Haldane Chern insulator in AB-stacked MoTe2/WSe2 moir\'e bilayers, which form a honeycomb moir\'e lattice with two sublattices residing in different layers. We show that the moir\'e bilayer filled with two charge particles per unit cell is a quantum spin Hall (QSH) insulator with a tunable charge gap. Under a small out-of-plane magnetic field, it becomes a Chern insulator with Chern number c=1 from magneto-transport studies. The results are qualitatively captured by a generalized Kane-Mele tight-binding Hamiltonian. The Zeeman field splits the QSH insulator into two halves of opposite valley--one with a positive and the other a negative moir\'e band gap. Our study highlights the unique potential of semiconductor moir\'e materials in engineering topological lattice Hamiltonians.

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Wenjin Zhao, Kaifei Kang, Lizhong Li, Charles Tschirhart, Evgeny Redekop, Kenji Watanabe, Takashi Taniguchi, Andrea Young, Jie Shan, Kin Fai Mak. 2022-07-05. Realization of the Haldane Chern insulator in a moir\'e lattice. https://arxiv.org/abs/2207.02312

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