Metal-insulator transition of charge-transfer salts based on unsymmetrical donor DMET and metal halide anions (DMET)4(MCl4)(TCE) 2 (M = Mn, Co, Cu, Zn; TCE = 1,1,2-trichloroethane)

Hiroshi Ito, Daichi Suzuki, Harutaka Watanabe, Hisaaki Tanaka, Shin Ichi Kuroda, Masamichi Umemiya, Norihito Kobayashi, Makoto Goto, Ken Ichi Sugiura, Hitoshi Miyasaka, Shinya Takaishi, Takashi Kajiwara, Masahiro Yamashita, Eiji Ohmichi, Toshihito Osada

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

New charge-transfer salts based on an unsymmetrical donor DMET [dimethyl(ethylenedithio)-diselenadithiafulvalene] and metal halide anions (DMET)4MIICl4(TCE)2 (M = Mn, Co, Cu, Zn; TCE = 1,1,2-trichloroethane) have been synthesized and characterized by transport and magnetic measurements. The crystal structures of the DMET salts are isostructural, consisting of a quasi-one-dimensional stack of DMET and insulating layers containing metal halide anions and TCE. Semimetallic band structures are calculated by the tight-binding approximation. Metal-insulator transitions are observed at TMI = 25, 15, 5-20, and 13 K for M = Mn, Co, Cu, and Zn, respectively. The M = Cu salt exhibits anisotropic conduction at ambient pressure, being semiconducting in the intralayer current direction but metallic for the interplane current direction, down to TMI. The metal-insulator transitions are suppressed under pressure. In the M = Co and Zn salts, large magnetoresistances with hysteresis are observed at low temperatures, on which Shubnikov-de Haas oscillations are superposed above 30 T. In the M = Cu salt, no hysteresis is observed but clear Shubnikov-de Haas oscillations are observed. The magnetoresistance is small and monotonic in the M = Mn salt. Paramagnetic susceptibilities of the spins of the magnetic ions are observed for the M = Mn, Co, and Cu salts with small negative Weiss temperatures of ∼1 K. In the nonmagnetic M = Zn salt, Pauli-like π-electron susceptibility that vanishes at TMI is observed. The ground state of the π-electron system is understood as being a spin density wave state caused by imperfect nesting of the Fermi surfaces. In this π-electron system, the magnetic ions of the M = Mn, Co, and Cu salts interact differently, exhibiting a variety of transport behaviors.

Original languageEnglish
Pages (from-to)8510-8518
Number of pages9
JournalJournal of the American Chemical Society
Volume129
Issue number27
DOIs
Publication statusPublished - 2007 Jul 11

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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