CONTROL OF CDW STATE IN HALOGEN-BRIDGED METAL-COMPLEXES

Chemical modifications of one-dimensional (1D) halogen-bridged mixed-valence metal complexes have been made in order to control the amplitude of the charge density wave (CDW) state in -M-X- chains (M=Pt, Pd or Ni, and X=Cl, Br or I). By changing chemical parameters, such as strength of hydrogen-bonds between the ligands and the counter anions, and the ionic radii of M and X, the characteristic diagram of the amplitude of CDW has been obtained as a function of the M-X-M distances. This provides a new basic idea for understanding the 1D electronic state of the M-X compounds, especially as related to dynamical phenomena originated in the charge transfer instability in the ground state and the photo-excited state.