Uniting the order and disorder dynamics in photoexcited VO2

Abstract

Photoinduced phase transition (PIPT) is always treated as a coherent process, but ultrafast disordering in PIPT is observed in recent experiments. Utilizing the real-time time-dependent density functional theory (rt-TDDFT) method, here, we track the motion of individual vanadium (V) ions during PIPT in VO2 and uncover that their coherent or disordered dynamics can be manipulated by tuning the laser fluence. We find that the photoexcited holes generate a force on each V-V dimer to drive their collective coherent motion, in competing with the thermal-induced vibrations. If the laser fluence is so weak that the photoexcited hole density is too low to drive the phase transition alone, the PIPT is a disordered process due to the interference of thermal phonons. We also reveal that the photoexcited holes populated by the V-V dimerized bonding states will become saturated if the laser fluence is too strong, limiting the timescale of photoinduced phase transition.

23 pages,10 figures

References in corpus (4)

• Evidence for a Structurally-driven Insulator-to-metal Transition in VO2: a View from the Ultrafast Timescale
• Universal phase dynamics in VO2 switches revealed by ultrafast operando diffraction
• Role of equilibrium fluctuations in light-induced order
• The critical role of hot carrier cooling in optically excited structural transitions

Cited by in corpus (7)

• Ultrafast lattice disordering can be accelerated by electronic collisional forces
• The photoinduced hidden metallic phase of monoclinic VO2 driven by local nucleation via a self-amplification process
• Origin of Immediate Damping of Coherent Oscillations in Photoinduced Charge Density Wave Transition
• Molecular orbital formation and metastable short-range ordered structure in VO${}_2$
• Light-induced phase transitions in vanadium dioxide: a tensor network study
• Evidence for bootstrap percolation dynamics in a photo-induced phase transition
• Ultrafast dynamics of atomic correlated disordering in photoinduced VO${}_2$