中国物理B ›› 2026, Vol. 35 ›› Issue (7): 77701-077701.doi: 10.1088/1674-1056/ae56e6

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Challenges in piezoelectric force microscopy characterization of sliding ferroelectric WTe2

Yichen Sun(孙一辰)1, Luqi Wei(魏鹿奇)1, Wencheng Fan(范文成)1, Weihao Sun(孙伟豪)1, Haonan Wang(王号南)1, Yaqiong Wang(王亚琼)1, Zhao Guan(关赵)1, Wenyi Tong(童文旖)1, Ke Qu(屈可)1, Zhenzhong Yang(杨振中)1, Binbin Chen(陈斌斌)1, Pinghua Xiang(向平华)1,2, Chungang Duan(段纯刚)1,2, and Ni Zhong(钟妮)1,2,†   

  1. 1 Key Laboratory of Polar Materials and Devices (MOE), Shanghai Center of Brain-inspired Intelligent Materials and Devices, Department of Electronics, East China Normal University, Shanghai 200241, China;
    2 Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
  • 收稿日期:2026-02-21 修回日期:2026-03-19 接受日期:2026-03-25 发布日期:2026-07-10
  • 通讯作者: Ni Zhong E-mail:nzhong@ee.ecnu.edu.cn
  • 基金资助:
    This work was supported by the National Key Research and Development Program of China (Grant Nos. 2024YFA14097000 and 2022YFA1402902), the National Natural Science Foundation of China (Grant Nos. 12474084, 12134003, 12374145, and 12574192), Chenguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission, ECNU (East China Normal University) Multifunctional Platform for Innovation (006, 001), and the Fundamental Research Funds for the Central Universities.

Challenges in piezoelectric force microscopy characterization of sliding ferroelectric WTe2

Yichen Sun(孙一辰)1, Luqi Wei(魏鹿奇)1, Wencheng Fan(范文成)1, Weihao Sun(孙伟豪)1, Haonan Wang(王号南)1, Yaqiong Wang(王亚琼)1, Zhao Guan(关赵)1, Wenyi Tong(童文旖)1, Ke Qu(屈可)1, Zhenzhong Yang(杨振中)1, Binbin Chen(陈斌斌)1, Pinghua Xiang(向平华)1,2, Chungang Duan(段纯刚)1,2, and Ni Zhong(钟妮)1,2,†   

  1. 1 Key Laboratory of Polar Materials and Devices (MOE), Shanghai Center of Brain-inspired Intelligent Materials and Devices, Department of Electronics, East China Normal University, Shanghai 200241, China;
    2 Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
  • Received:2026-02-21 Revised:2026-03-19 Accepted:2026-03-25 Published:2026-07-10
  • Contact: Ni Zhong E-mail:nzhong@ee.ecnu.edu.cn
  • Supported by:
    This work was supported by the National Key Research and Development Program of China (Grant Nos. 2024YFA14097000 and 2022YFA1402902), the National Natural Science Foundation of China (Grant Nos. 12474084, 12134003, 12374145, and 12574192), Chenguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission, ECNU (East China Normal University) Multifunctional Platform for Innovation (006, 001), and the Fundamental Research Funds for the Central Universities.

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摘要： Sliding ferroelectricity, an emerging ferroelectric mechanism in 2D systems whose polarization arises from interlayer charge transfer, has attracted considerable attention due to its unique switching behavior, such as superior endurance and high switching speed. However, its experimental characterization remains challenging due to the low polarizability and technical difficulties. Using piezoelectric force microscopy (PFM), we investigate ${\rm T}_{\rm d}$-WTe$_2$ as a model sliding ferroelectric system, aiming to fill the gap in the characterization of sliding ferroelectricity from a microscopic perspective. We observed ferroelectric-like PFM phase contrast and amplitude hysteresis in few-layer (1-4 L) WTe$_{2}$ flakes under ambient conditions, in contrast to the theoretical predictions for flakes thicker than 2 L. Surface oxidation of WTe$_{2}$ has been identified by Raman and other characterization techniques. Therefore, similar PFM characterization has been carried out on the flakes covered by h-BN, which prevented WTe$_{2}$ from oxidation, and no ferroelectric behavior could be found. Consequently, the ferroelectric-like PFM phenomena are attributed to oxidation rather than intrinsic ferroelectricity in WTe$_2$. Combined with analyses of PFM testing principles and the mechanism of sliding ferroelectricity, we identify the limitations and challenges of PFM in characterizing sliding ferroelectricity. This work provides valuable insights for the subsequent characterization and application of related sliding ferroelectrics.

关键词: 2D ferroelectric, sliding ferroelectric, piezoelectric force microscopy (PFM)

Abstract: Sliding ferroelectricity, an emerging ferroelectric mechanism in 2D systems whose polarization arises from interlayer charge transfer, has attracted considerable attention due to its unique switching behavior, such as superior endurance and high switching speed. However, its experimental characterization remains challenging due to the low polarizability and technical difficulties. Using piezoelectric force microscopy (PFM), we investigate ${\rm T}_{\rm d}$-WTe$_2$ as a model sliding ferroelectric system, aiming to fill the gap in the characterization of sliding ferroelectricity from a microscopic perspective. We observed ferroelectric-like PFM phase contrast and amplitude hysteresis in few-layer (1-4 L) WTe$_{2}$ flakes under ambient conditions, in contrast to the theoretical predictions for flakes thicker than 2 L. Surface oxidation of WTe$_{2}$ has been identified by Raman and other characterization techniques. Therefore, similar PFM characterization has been carried out on the flakes covered by h-BN, which prevented WTe$_{2}$ from oxidation, and no ferroelectric behavior could be found. Consequently, the ferroelectric-like PFM phenomena are attributed to oxidation rather than intrinsic ferroelectricity in WTe$_2$. Combined with analyses of PFM testing principles and the mechanism of sliding ferroelectricity, we identify the limitations and challenges of PFM in characterizing sliding ferroelectricity. This work provides valuable insights for the subsequent characterization and application of related sliding ferroelectrics.

Key words: 2D ferroelectric, sliding ferroelectric, piezoelectric force microscopy (PFM)

中图分类号:  (Ferroelectricity and antiferroelectricity)

  • 77.80.-e
77.90.+k (Other topics in dielectrics, piezoelectrics, and ferroelectrics and their properties) 77.80.Dj (Domain structure; hysteresis)