Structural, electrical, magnetic, and optical properties of bis-benzene-1,2-dithiolato-Au(IV) crystals

N. C. Schiødt, T. Bjørnholm, K. Bechgaard, J. J. Neumeier, C. Allgeier, C. S. Jacobsen, and N. Thorup
Phys. Rev. B 53, 1773 – Published 15 January 1996
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Abstract

Analysis of x-ray diffraction from a single crystal of bis-benzene-1,2-dithiolato-Au(IV) [Au(bdt)2] at 125 K reveals a superstructure along the stacks of Au(bdt)2 molecules corresponding to a dimerization of the molecules along the stack. Within a dimer, intermolecular sulfur-sulfur contacts are shortened from 3.7 to 3.6 Å whereas a lengthening to about 3.8 Å is found between dimers. Electrical resistivity measured by a four-probe method between 230 and 450 K uncovers an activated resistivity with a characteristic energy of 0.30 eV. The room-temperature conductivity at zero applied pressure is 0.11 Ω1 m1 rising smoothly to 0.67 Ω1 m1 at 0.55 GPa isotropic pressure. The magnetic susceptibility χ is low compared to the spin susceptibility of a system with one free spin per molecule. An activated behavior of χ is observed, which gives rise to a monotonic increase in χ at between 275 and 420 K. Reflectivity measurements along the b axis (stacking direction) of a single crystal of Au(bdt)2 shows a transition around 5000 cm1 (0.6 eV) possessing an oscillator strength ≈0.5 electron/molecule. Along the c axis an absorption centered around 8000 cm1 is observed. The first transition (5000 cm1) is attributed to an intermolecular charge-transfer process while the latter transition (8000 cm1) most likely corresponds to an intramolecular excitation. The physical data presented are discussed in the context of a soft Mott insulator.

  • Received 18 May 1995

DOI:https://doi.org/10.1103/PhysRevB.53.1773

©1996 American Physical Society

Authors & Affiliations

N. C. Schiødt, T. Bjørnholm*, and K. Bechgaard

  • Centre for Interdisciplinary Studies of Molecular Interactions, Department of Chemistry, Symbion Science Park, University of Copenhagen, Fruebjergvej 3, DK-2100 Ø, Copenhagen, Denmark

J. J. Neumeier and C. Allgeier§

  • Sektion Physik der Ludwig-Maximilian Universität, Schellingstrasse 4/IV, 80799 München, Germany

C. S. Jacobsen

  • Physics Department, Technical University of Denmark, DK-2800, Lyngby, Denmark

N. Thorup

  • Structural Chemistry Group, Chemistry Department B, Technical University of Denmark, DK-2800, Lyngby, Denmark

  • *Author to whom correspondence should be addressed.
  • Present address: MST-10, Mail Stop k764, Los Alamos National Laboratory, Los Alamos, NM 87545.
  • Present address: Osram GmbH, Hellabrunner Str. 1, 81543, Münich, Germany.
  • §Present address: Physics Department, RISØ National Laboratory, P.O. Box 49, DK-4000 Roskilde, Denmark.

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Issue

Vol. 53, Iss. 4 — 15 January 1996

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