Ultrafast Phase Control in One-Dimensional Correlated Electron Systems

Abstract

One-dimensional (1D) correlated electron systems are good targets for the exploration of photoinduced phase transitions (PIPTs). This is because photocarrier generations and/or charge transfer (CT) excitations by lights can stimulate instabilities inherent to the 1D nature of electronic states through strong electron–electron interactions and electron(spin)–lattice interactions. In this paper, we review the ultrafast dynamics of three typical PIPTs observed in 1D correlated electron systems: 1) a photoinduced transition from a Mott insulator to a metal in a halogen-bridged Ni-chain compound, [Ni(chxn) 2 Br]Br 2 (chxn = cyclohexanediamine); 2) a photoinduced melting of a spin-Peierls phase in an organic CT compound, K-tetracyanoquinodimethane (TCNQ); 3) a photoinduced transition between neutral (N) and ionic (I) states in an organic CT compound, tetrathiafulvalene- p -chloranil (TTF-CA). The primary dynamics of these PIPTs are discussed on the basis of the results of femtosecond pump–probe spectroscopy.