Dresden 2026 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 49: Correlated Electrons: Charge Order

TT 49.2: Talk

Wednesday, March 11, 2026, 11:00–11:15, HSZ/0101

Dynamics of CDW puddles in bulk 2H-NbSe₂ — •Shreya Kumbhakar^1,2, Marina Esposito³, Anjan Kumar N M¹, Sushmita Chandra⁴, Claudia Felser⁴, Kornelius Nielsch^1,2, Nicola Poccia^2,3, Stefan Kaiser¹, and Golam Haider² — ¹TU Dresden — ²IFW Dresden — ³U. Naples — ⁴MPI CPfS

In complex materials, incommensurate charge-density-wave (CDW) is often formed from local commensurate domains or puddles. Measuring the dynamics of these puddles, we probe the effect of lattice pinning, electronic correlations and disorder on emergent phases. Raman scattering reveals a Fano lineshape of the CDW amplitude mode, indicating strong coupling between the interlayer shear vibration and the CDW order. Time-resolved reflectivity shows a coherent overdamped oscillation below the CDW transition temperature, indicating a new low-frequency hybrid phonon-CDW amplitude mode around 0.15 THz. This we identify as the CDW puddle emerging from the strong Fano coupling. Our measurements further reveal a transition at  14 K, pointing to a possible crossover of the dominant commensuration order of these puddles. These results highlight how the layered structure affects the CDW order, which is crucial for the design and understanding of novel vdW heterostructures.

Keywords: Charge density wave; Amplitude mode; Fano resonance; Ultrafast spectroscopy; Raman scattering