Quench of the electronic order in a strongly-coupled charge-density-wave system by enhanced lattice fluctuations

Abstract: Charge-density-wave (CDW) materials having a strong electron-phonon coupling provide a powerful platform for investigating the intricate interplay between lattice fluctuations and a macroscopic quantum order. Using time- and angle-resolved photoemission spectroscopy (TR-ARPES), we reveal that the CDW gap closure in VTe2 is dominated by an incoherent process evolving on a sub-picosecond timescale, challenging the conventional view that the gap dynamics is primarily governed by the excitation of the CDW amplitude modes. Our findings, supported by a three-temperature model, show that the CDW gap evolution can be described by considering the population of a subset of strongly-coupled optical phonon modes, which leads to an increase in the lattice fluctuations. This microscopic framework extends beyond VTe2, offering a universal perspective for understanding the light-induced phase transition in strongly-coupled CDW systems.