Strongly-coupled hybrid lattice-plasmons in layered cuprates

Fuente: arXiv
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Autores principales: Xu, Ke-Jun, Giles-Donovan, Nathan, Agrestini, Stefano, Choi, Jaewon, Garcia-Fernandez, Mirian, Zhou, Kejin, He, Junfeng, Rotundu, Costel R., Lee, Young S., Devereaux, Thomas P., Shen, Zhi-Xun, Lee, Dung-Hai, Birgeneau, Robert J., Lee, Wei-Sheng
Formato: Preprint
Publicado: 2026
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author Xu, Ke-Jun
Giles-Donovan, Nathan
Agrestini, Stefano
Choi, Jaewon
Garcia-Fernandez, Mirian
Zhou, Kejin
He, Junfeng
Rotundu, Costel R.
Lee, Young S.
Devereaux, Thomas P.
Shen, Zhi-Xun
Lee, Dung-Hai
Birgeneau, Robert J.
Lee, Wei-Sheng
author_facet Xu, Ke-Jun
Giles-Donovan, Nathan
Agrestini, Stefano
Choi, Jaewon
Garcia-Fernandez, Mirian
Zhou, Kejin
He, Junfeng
Rotundu, Costel R.
Lee, Young S.
Devereaux, Thomas P.
Shen, Zhi-Xun
Lee, Dung-Hai
Birgeneau, Robert J.
Lee, Wei-Sheng
contents Metallic systems with delocalized valence electrons host collective charge density oscillations known as plasmons. On the other hand, conventional insulators do not have free electrons and the low energy charge degrees of freedom are pinned to the ions. The fate of the collective charge excitations in the intermediate regime is an outstanding question. This problem is especially important for strongly correlated systems such as the layered cuprates, where unconventional superconductivity and other emergent phenomena arise from valence electrons on the border between Mott localization and itinerancy. Using resonant inelastic X-ray scattering, we track this evolution in the prototypical electron-doped cuprate Nd2-xCexCuO4. We find a continuous transformation of the low-energy charge response: from an acoustic plasmon in the metallic regime, to a gapped hybrid mode at intermediate doping, and finally to a nearly dispersionless 139 meV excitation at half filling. Remarkably, the 139 meV excitation has approximately twice the energy of the oxygen breathing phonon responsible for the dispersion kink observed in angle-resolved photoemission spectroscopy, and is consistent with a putative 2-phonon excitation observed in Raman spectroscopy. These results establish a unified picture of collective charge excitations across the phase diagram of electron-doped cuprates, showing that such modes persist across the Mott transition via strong coupling to lattice degrees of freedom and revealing a missing link in the charge dynamics of carrier doped Mott insulators.
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id arxiv_https___arxiv_org_abs_2605_29100
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Strongly-coupled hybrid lattice-plasmons in layered cuprates
Xu, Ke-Jun
Giles-Donovan, Nathan
Agrestini, Stefano
Choi, Jaewon
Garcia-Fernandez, Mirian
Zhou, Kejin
He, Junfeng
Rotundu, Costel R.
Lee, Young S.
Devereaux, Thomas P.
Shen, Zhi-Xun
Lee, Dung-Hai
Birgeneau, Robert J.
Lee, Wei-Sheng
Strongly Correlated Electrons
Materials Science
Superconductivity
Metallic systems with delocalized valence electrons host collective charge density oscillations known as plasmons. On the other hand, conventional insulators do not have free electrons and the low energy charge degrees of freedom are pinned to the ions. The fate of the collective charge excitations in the intermediate regime is an outstanding question. This problem is especially important for strongly correlated systems such as the layered cuprates, where unconventional superconductivity and other emergent phenomena arise from valence electrons on the border between Mott localization and itinerancy. Using resonant inelastic X-ray scattering, we track this evolution in the prototypical electron-doped cuprate Nd2-xCexCuO4. We find a continuous transformation of the low-energy charge response: from an acoustic plasmon in the metallic regime, to a gapped hybrid mode at intermediate doping, and finally to a nearly dispersionless 139 meV excitation at half filling. Remarkably, the 139 meV excitation has approximately twice the energy of the oxygen breathing phonon responsible for the dispersion kink observed in angle-resolved photoemission spectroscopy, and is consistent with a putative 2-phonon excitation observed in Raman spectroscopy. These results establish a unified picture of collective charge excitations across the phase diagram of electron-doped cuprates, showing that such modes persist across the Mott transition via strong coupling to lattice degrees of freedom and revealing a missing link in the charge dynamics of carrier doped Mott insulators.
title Strongly-coupled hybrid lattice-plasmons in layered cuprates
topic Strongly Correlated Electrons
Materials Science
Superconductivity
url https://arxiv.org/abs/2605.29100