Giant Shubnikov-de Haas oscillation and the new metallic state in the organic τ-type conductors

T. Konoike, K. Murata, K. Iwashita, H. Yoshino, T. Sasaki, K. Hiraki, T. Takahashi, Y. Nishio, K. Kajita, H. Tajima, G. Papavassiliou

Research output: Contribution to journalConference articlepeer-review

10 Citations (Scopus)


Two-dimensional organic τ-type conductors show metallic temperature dependence of resistivity down to Tmin = 30-50 K, below which a resistivity upturn is observed. A large negative magnetoresistance appears below Tmin suddenly in temperature. Below about 4 K, magnetoresistance in any direction is extremely hysteretic in field-, temperature- or field-angle-sweep, and ρ(H//plane) shows switching between two- and four-fold depending on magnetic and thermal history, indicating magnetic domain generation. Static susceptibility shows slight ferromagnetic component. NMR is in favor of anti-ferromagnetism below about 15 K. These two results imply that the system is a weak ferromagnetic one. Preliminary optical reflectance and specific heat studies implied metallic state at low temperature, but no clear-cut proof has been shown whether or not the ground state is metallic. This report presents giant Shubnikov de Haas (SdH) oscillation in both τ-(EDO-S,S-DMEDT-TTF)2(AuBr2)1+y, and τ-(P-S,S-DMEDT-TTF)2(AuBr2)1+y, (y ∼ 0.75), which is a clear evidence for the metallic ground state. However, the observed Fermi surfaces (FS) are 0.65 and 6.1% of the first Brillouin zone for τ-(EDO-S,S-DMEDT-TTF)2(AuBr2)1+y, and 2.3 and 6.9% for τ-(P-S,S-DMEDT-TTF)2(AuBr2)1+y, (y ∼ 0.75), which suggest extremely small FS pockets, and were not expected by the previous band calculation. Further, it is surprising that the Dingle temperature was around 1 K, indicating unexpectedly clean, while residual resistivity ratio is about 1. We note that the fundamental oscillation of 0.65% is already n = 2 state, which is already next to the Landau quantum limit.

Original languageEnglish
Pages (from-to)1245-1248
Number of pages4
JournalJournal of Physics and Chemistry of Solids
Issue number6-8
Publication statusPublished - 2002 Jun
Externally publishedYes
EventProceedings of the 8th ISSP International Symposium - Tokyo, Japan
Duration: 2001 Nov 22001 Nov 5


  • A. Organic compounds
  • D. Electronic structure
  • D. Fermi surface
  • D. Magnetic properties
  • D. Transport properties

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics


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