Ultrafast Photoconversion from Charge Density Wave State to Mott–Hubbard State in One-Dimensional Extended Peierls–Hubbard System of Br-Bridged Pd Compound

Abstract

Photoconversion from a charge density wave (CDW) state to a Mott–Hubbard (MH) state in a one-dimensional (1D) extended Peierls–Hubbard system is observed by femtosecond (fs) reflection spectroscopy. The Br-bridged Pd compound examined is located near the CDW-MH phase boundary, and the irradiation of a fs laser pulse causes the instantaneous formation of a 1D MH domain without alternation of bridging-Br displacements. This result demonstrates the important role of intersite Coulomb repulsion in the transition, and in the stabilization of the CDW state. The formation of the MH domain is followed by a coherent oscillation with a period of 360 fs attributable to the relaxation of the bridging-Br displacements coupled with the charge-transfer between neighboring Pd ions.