Dynamics of Charge-Density-Wave puddles in 2$H$-NbSe$_2$

Shreya Kumbhakar; Marina Esposito; Anjan Kumar N M; Liwen Feng; Tommaso Confalone; Vasilisa Gerega; Flavia Lo Sardo; Rafiqul Alam; Davide Masarotti; Francesco Tafuri; Thomas Böhm; Mahmoud Abdel-Hafiez; Sushmita Chandra; Claudia Felser; Kornelius Nielsch; Nicola Poccia; Stefan Kaiser; Golam Haider

arXiv · 2603.03980

Dynamics of Charge-Density-Wave puddles in 2$H$-NbSe$_2$

Shreya Kumbhakar·Marina Esposito·Anjan Kumar N M·Liwen Feng·Tommaso Confalone·Vasilisa Gerega·Flavia Lo Sardo·Rafiqul Alam·Davide Masarotti·Francesco Tafuri·Thomas Böhm·Mahmoud Abdel-Hafiez·Sushmita Chandra·Claudia Felser·Kornelius Nielsch·Nicola Poccia·Stefan Kaiser·Golam Haider

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Abstract

Electronic phases in quantum materials are often governed by nanoscale inhomogeneity, where local order develops within spatially confined regions or puddles. A prominent example is an incommensurate charge-density-wave (I-CDW) that comprises locally commensurate domains. In 2$H$-NbSe$_2$, such an I-CDW state persists alongside lattice anharmonicity and superconductivity, raising fundamental questions about the dynamical stabilization of CDW order in puddles. Here, we probe the puddle-dynamics in 2$H$-NbSe$_2$. Raman scattering reveals a strong Fano-coupling between the interlayer shear vibration and the CDW amplitude mode. Time-resolved reflectivity measurement shows a low-frequency ~0.15 THz coherent overdamped oscillation onsetting within the CDW regime at ~17 K, pointing towards a so far unexplored transition. This we identify as a Fano-coupled phonon-CDW hybrid emerging from the collective dynamics of CDW puddles. We establish a framework for capturing intertwinned glassy dynamics with an overdamped oscillatory model. Such dynamics in 2H-NbSe2 highlight how lattice pinning and electronic correlations in layered materials affect the CDW order, which is crucial for the design of novel Van der Waals devices.

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Shreya Kumbhakar, Marina Esposito, Anjan Kumar N M, Liwen Feng, Tommaso Confalone, Vasilisa Gerega, Flavia Lo Sardo, Rafiqul Alam, Davide Masarotti, Francesco Tafuri, Thomas Böhm, Mahmoud Abdel-Hafiez, Sushmita Chandra, Claudia Felser, Kornelius Nielsch, Nicola Poccia, Stefan Kaiser, Golam Haider. 2026-03-04. Dynamics of Charge-Density-Wave puddles in 2$H$-NbSe$_2$. https://arxiv.org/abs/2603.03980

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