Photo-Induced Phase Transition in Charge Order Systems --Charge Frustration and Interplay with Lattice--

摘要

Lattice effects on photo-excited states in interacting charge frustratedsystem are examined. Real time dynamics in the interacting spinless fermionmodel on a triangular lattice coupled to lattice vibration are analyzed byapplying the exact diagonalization method combined with the classical equationof motion. A photo-induced phase transition from the horizontal stripe-typecharge order (CO) to the 3-fold CO occurs through a characteristic intermediatetime domain. By analyzing the time evolution in detail, we find that thischaracteristic dynamics are seen when the electron and lattice sectors are notcomplementary to each other but show cooperative time evolutions. We also findthat there are threshold values in the optical fluorescence andelectron-lattice coupling for emergence of the photo-induced 3-fold CO. Thedynamics are distinct from those from the vertical stripe-type CO, in which amonotonic CO melting occurs. A scenario of the photo-induced CO phasetransition with lattice degree of freedom is presented from a view point ofcharge frustration.