Neutron Scattering Study of Long-Timescale Charge Density Wave dynamics in 1T-TiSe₂*

Time-resolved elastic neutron scattering combined with rapid laser heating was employed to investigate the dynamics of the charge density wave (CDW) over long timescales in 1T-TiSe₂. Superlattice Bragg peaks such as (-3/2, -3/2, 3/2), which reflect the periodic lattice distortion (PLD) below the ≈200 K CDW transition, were monitored during alternating 120 s laser-on and 180 s laser-off cycles. Although the sample equilibrates thermally within ≲100 ms, the PLD melts with a characteristic decay rate of 2.6 s, which is an order of magnitude slower than the thermal response, demonstrating a nonthermal CDW melting pathway likely linked to the loss of superlattice phonon modes. Upon laser removal, the CDW peak recovers slowly over 30–40 s, indicating that the re-emergence of the CDW is a temperature-driven process. These findings highlight the presence of distinct timescales in phase transition dynamics and open new avenues of research with potential relevance for future applications.