Electronic Phonons in a Moiré Electron Crystal

Fuente: arXiv
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Main Authors: Zhao, Yan, Hou, Yuhang, Cai, Xiangbin, Ru, Shihao, Yang, Shunshun, Zhang, Yan, Dai, Xuran, Shang, Qiuyu, Rasmita, Abdullah, Pan, Haiyang, Watanabe, Kenji, Taniguchi, Takashi, Cai, Hongbin, Yu, Hongyi, Gao, Weibo
Format: Preprint
Published: 2025
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author Zhao, Yan
Hou, Yuhang
Cai, Xiangbin
Ru, Shihao
Yang, Shunshun
Zhang, Yan
Dai, Xuran
Shang, Qiuyu
Rasmita, Abdullah
Pan, Haiyang
Watanabe, Kenji
Taniguchi, Takashi
Cai, Hongbin
Yu, Hongyi
Gao, Weibo
author_facet Zhao, Yan
Hou, Yuhang
Cai, Xiangbin
Ru, Shihao
Yang, Shunshun
Zhang, Yan
Dai, Xuran
Shang, Qiuyu
Rasmita, Abdullah
Pan, Haiyang
Watanabe, Kenji
Taniguchi, Takashi
Cai, Hongbin
Yu, Hongyi
Gao, Weibo
contents Collective quantum phenomena, such as the excitation of composite fermions1, spin waves2, and exciton condensation3,4, can emerge in strongly correlated systems like the fractional quantum Hall states5, spin liquids6, or excitonic insulators7. Two-dimensional (2D) moiré superlattices have emerged as a powerful platform for exploring such correlated phases and their associated collective excitations8,9. Specifically, electron crystals stabilized by longrange Coulomb interactions may host collective vibrational excitations emerging from electron correlations10, termed electronic phonons, which are fundamentally distinct from atomic lattice phonons. Despite theoretical prediction of their existence in moiré electron crystals11, direct experimental evidence has remained elusive. Here we report the observation of electronic phonons in the Mott insulating and stripe phases of a WS2/WSe2 moiré superlattice, achieved through light scattering measurements. The phonon energies, temperature and filling factor dependencies, along with theoretical modeling, corroborate their origin as collective vibrations of a correlated electron crystal. Polarization-resolved measurements further indicate rotational symmetry breaking in the Mott state. Notably, these electronic phonons exhibit strong tunability in energy, intensity, and polarization under external electric or magnetic fields, highlighting rich and controllable lattice dynamics of the electron crystal. These findings provide direct spectroscopic evidence for the electronic crystalline nature of correlated phases, opening avenues for probing and manipulating collective excitations in correlated electron systems.
format Preprint
id arxiv_https___arxiv_org_abs_2512_18217
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Electronic Phonons in a Moiré Electron Crystal
Zhao, Yan
Hou, Yuhang
Cai, Xiangbin
Ru, Shihao
Yang, Shunshun
Zhang, Yan
Dai, Xuran
Shang, Qiuyu
Rasmita, Abdullah
Pan, Haiyang
Watanabe, Kenji
Taniguchi, Takashi
Cai, Hongbin
Yu, Hongyi
Gao, Weibo
Strongly Correlated Electrons
Mesoscale and Nanoscale Physics
Collective quantum phenomena, such as the excitation of composite fermions1, spin waves2, and exciton condensation3,4, can emerge in strongly correlated systems like the fractional quantum Hall states5, spin liquids6, or excitonic insulators7. Two-dimensional (2D) moiré superlattices have emerged as a powerful platform for exploring such correlated phases and their associated collective excitations8,9. Specifically, electron crystals stabilized by longrange Coulomb interactions may host collective vibrational excitations emerging from electron correlations10, termed electronic phonons, which are fundamentally distinct from atomic lattice phonons. Despite theoretical prediction of their existence in moiré electron crystals11, direct experimental evidence has remained elusive. Here we report the observation of electronic phonons in the Mott insulating and stripe phases of a WS2/WSe2 moiré superlattice, achieved through light scattering measurements. The phonon energies, temperature and filling factor dependencies, along with theoretical modeling, corroborate their origin as collective vibrations of a correlated electron crystal. Polarization-resolved measurements further indicate rotational symmetry breaking in the Mott state. Notably, these electronic phonons exhibit strong tunability in energy, intensity, and polarization under external electric or magnetic fields, highlighting rich and controllable lattice dynamics of the electron crystal. These findings provide direct spectroscopic evidence for the electronic crystalline nature of correlated phases, opening avenues for probing and manipulating collective excitations in correlated electron systems.
title Electronic Phonons in a Moiré Electron Crystal
topic Strongly Correlated Electrons
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2512.18217