Mechanism for Synchronization of Charge Oscillations in Dimer Lattices

Abstract

We discuss the mechanism and the conditions for the appearance of synchronized charge oscillations which have been observed experimentally and theoretically after strong photoexcitation of dimerized systems. In the Hubbard model with on-site repulsion, the Bloch equations for a wave-number-dependent pseudospin -- whose components describe the charge-density difference, current density, and bond density between the two sublattices -- involve an alternatingly tilted pseudomagnetic field, which assists the synchronization of pseudospins with different wave numbers, irrespective of the initial condition. This fact is numerically confirmed by the dynamics in finite lattices based on the exact diagonalization method. In the presence of nearest-neighbor repulsion, however, the synchronization can be hindered by excitons. Therefore, the excitation of a sufficiently large density of free electron-hole pairs, but low density of excitons, is needed to achieve synchronization.

9 pages, 8 figures

References in corpus (10)

• Electrodynamics of Correlated Electron Materials
• Unconventional critical behaviour in a quasi-two-dimensional organic conductor
• Nonlinear light-matter interaction at terahertz frequencies
• Nonthermal antiferromagnetic order and nonequilibrium criticality in the Hubbard model
• Dynamical band flipping in fermionic lattice systems: An ac-field-driven change of the interaction from repulsive to attractive
• Photo-induced enhancement of excitonic order
• Optical freezing of charge motion in an organic conductor
• Coupling-dependent rates of energy transfers from photoexcited Mott insulators to lattice vibrations
• High-harmonic generation in spin-orbit coupled systems
• Competition between Interactions and Randomness in Photoinduced Synchronization of Charge Oscillations on a Dimer Lattice