Photoinduced Phase Transitions in MMX-Chain Compounds - Material Designs and New Physical Properties in MX-and MMX-Chain Compounds - page 225

Chapter 11
Photoinduced Phase Transitions in MMX-Chain
Compounds

Hiroyuki Matsuzaki and Hiroshi Okamoto

11.1 Introduction

As mentioned in Chap. 5, 1D electronic systems are good targets for the exploration
of characteristic photoinduced phase transitions (PIPTs), since photocarrier
generations and/or charge-transfer excitations by photoirradiation can stimulate
instabilities inherent to the 1D nature of electronic states through strong
electron-electron interactions and electron (spin)-lattice interactions. Actually,
MX - chain compounds, the prototypical 1D electronic systems, exhibit characteris-
tic PIPTs such as the photoinduced transition from Mott insulator to metal, the
photoinduced transition from charge-density-wave state to Mott-Hubbard state,
and photoinduced transition from charge-density-wave state to metallic state (see
Chap. 5). The halogen-bridged binuclear metal compounds (the MMX-chain
compounds) focused here are other typical 1D electronic systems with strong
electron-electron interactions and electron (spin)-lattice interactions and are
promising targets for realizing characteristic PIPTs. In this chapter, we review the
PIPTs observed in the MMX-chain compounds.
The materials discussed here are iodine-bridged binuclear platinum compounds
(PtPtI-chain compounds), in which PtPtI chains dominate their electronic properties
[ 1 - 5 ]. Before discussing the phase control and PIPT in the PtPtI-chain compound,
we briefly review its crystal and electronic structure. This compounds have purely