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arXiv · 2509.16493

Dynamics of a jointly commensurate moiré charge density wave

Kyoung Hun Oh·Yifan Su·Honglie Ning·B. Q. Lv·Alfred Zong·Dong Wu·Qiaomei Liu·Gyeongbo Kang·Hyeongi Choi·Hyun-Woo J. Kim·Seunghyeok Ha·Jaehwon Kim·Suchismita Sarker·Jacob P. C. Ruff·Xiaozhe Shen·Duan Luo·Stephen Weathersby·Patrick Kramer·Xinxin Cheng·Dongsung Choi·Doron Azoury·Masataka Mogi·B. J. Kim·N. L. Wang·Hoyoung Jang·Nuh Gedik
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Abstract

The advent of two-dimensional moiré systems has revolutionized the exploration of phenomena arising from strong correlations and nontrivial band topology. Recently, a moiré superstructure formed by two coexisting charge density waves (CDWs) with slightly mismatched wavevectors has been realized. These incommensurate CDWs can collectively exhibit commensurability, resulting in the jointly commensurate CDW (JC-CDW) and establishing a new paradigm for controlling moiré potential and periodicity. Achieving such functionality, however, hinges on a key open question: how do the amplitude, phase coherence, and periodicity of this order respond to external perturbations? Here, we address this question using a suite of time- and momentum-resolved diffraction and spectroscopic techniques to probe light-induced CDW dynamics in EuTe$_4$. Our time-resolved diffraction measurements distinguish the instantaneous quenching of the JC-CDW amplitude, as verified by time-resolved photoemission spectroscopy, from the much slower evolution of phase fluctuations. Furthermore, while the JC-CDW wavevector remains locked along the CDW direction upon photoexcitation, indicating a preserved moiré periodicity, the correlation length of JC-CDW shows an exclusive reduction perpendicular to its wavevector, unveiling the formation of previously unexplored shear-type defects. Together, this multimodal methodology reconstructs the spatiotemporal evolution of the JC-CDW upon excitation. These findings not only highlight the remarkable robustness of JC-CDWs out of equilibrium, but also provide insight into optical manipulation and engineering of moiré quantum materials through defect control.

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Kyoung Hun Oh, Yifan Su, Honglie Ning, B. Q. Lv, Alfred Zong, Dong Wu, Qiaomei Liu, Gyeongbo Kang, Hyeongi Choi, Hyun-Woo J. Kim, Seunghyeok Ha, Jaehwon Kim, Suchismita Sarker, Jacob P. C. Ruff, Xiaozhe Shen, Duan Luo, Stephen Weathersby, Patrick Kramer, Xinxin Cheng, Dongsung Choi, Doron Azoury, Masataka Mogi, B. J. Kim, N. L. Wang, Hoyoung Jang, Nuh Gedik. 2026-07-03. Dynamics of a jointly commensurate moiré charge density wave. https://doi.org/10.1038/s41467-026-77670-2

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