Ultrafast Dynamics of the Charge Density Wave State in Layered CuxTiSe2

2016/12/06 by David B. Lioi, Richard D. Schaller, Lioi, D. B. +5
Engineering · Materials Science · #2D Materials and Applications #Chalcogenide Semiconductor Thin Films #FOS: Physical sciences #Quantum Dots Synthesis And Properties #Strongly Correlated Electrons (cond-mat.str-el)

paper · pdf · doi:10.48550/arxiv.1612.01838

openalex publication_date 2016/12/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We report on a transient optical reflectivity study of the charge density wave (CDW) in CuxTiSe2 single crystals. Our measurements reveal that the system undergoes a quantum phase transition at x=0.04 from a strong commensurate CDW (x<0.04) to a soft incommensurate CDW (x>0.04). We find that the cooperative driving mechanisms for the commensurate CDW, the excitonic insulator mechanism and the soft L₁^- phonon mode, decouple at x=0.04 with the observed fluctuations in the folded Se-4p band dominating the transition. We also demonstrate a loss of coherence in the A_1g phonon with increased copper intercalation of the parent lattice, indicating a loss of long-range lattice order. These findings provide compelling evidence that TiSe2 undergoes a quantum phase transition upon copper intercalation from a state of commensurate charge order to a state with a different symmetry in which the new charge order coexists with the superconducting phase.

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