2019/09/24 by Gero Storeck, Storeck, Gero, Jan Horstmann +13
Materials Science · Physics and Astronomy · #Electronic and Structural Properties of Oxides #FOS: Physical sciences #Organic and Molecular Conductors Research #Semiconductor Quantum Structures and Devices #Strongly Correlated Electrons (cond-mat.str-el)
paper · pdf · doi:10.48550/arxiv.1909.10793
openalex publication_date 2019/09/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We study the non-equilibrium structural dynamics of the incommensurate and\nnearly-commensurate charge-density wave phases in 1T-TaS2. Employing\nultrafast low-energy electron diffraction (ULEED) with 1 ps temporal\nresolution, we investigate the ultrafast quench and recovery of the CDW-coupled\nperiodic lattice distortion. Sequential structural relaxation processes are\nobserved by tracking the intensities of main lattice as well as satellite\ndiffraction peaks as well as the diffuse scattering background. Comparing\ndistinct groups of diffraction peaks, we disentangle the ultrafast quench of\nthe PLD amplitude from phonon-related reductions of the diffraction intensity.\nFluence-dependent relaxation cycles reveal a long-lived partial suppression of\nthe order parameter for up to 60 picoseconds, far outlasting the initial\namplitude recovery and electron-phonon scattering times. This delayed return to\na quasi-thermal level is controlled by lattice thermalization and coincides\nwith the population of zone-center acoustic modes, as evidenced by a structured\ndiffuse background. The long-lived non-equilibrium order parameter suppression\nsuggests hot populations of CDW-coupled lattice modes. Finally, a broadening of\nthe superlattice peaks is observed at high fluences, pointing to a nonlinear\ngeneration of phase fluctuations.\n