J. Phys. IV France 12 (2002) Pr9-381
DOI: 10.1051/jp4:20020443

FISDW in quasi-one dimensional organic conductors with the dimerized gap due to anion ordering

N. Matsunaga^{1, 2, 3}, A. Ayari^{2, 3}, P. Moncea^{2, 3}, K. Yamashita¹, A. Ishikawa¹, K. Nomura¹, M. Watanabe⁴, J. Yamada⁴ and S. Nakatsuji<sup>4

1</sup>  Division of Physics, Hokkaido University, Sapporo 060-0810, Japan
²  CRTBT-CNRS, Laboratoire Associé a l'UJF, BP. 166, 38042 Grenoble cedex 9, France
³  Grenoble High Field Laboratory, CNRS/MPI-FKF, BP. 166, 38042 Grenoble cedex 9, France
⁴  Department of Material Science, Himeji Institute of Technology, Kamigohri 678-1297, Japan

Abstract
Magnetoresistance and Hall resistance measurements have been carried out in the FISDW phase of deuterated (TMTSF) ₂C1O ₄ for various cooling rates through the anion ordering temperature. The Hall resistance in the intermediate cooled state, observed a very stable quantum Hall state above 9.0 T for slowly cooled, shows a step-like change from the phase between 10 and 17 T to the phase between 20 and 25 T with hysteresis between 14 and 21 T. This result suggests that there is a new phase transition around 15 T in deuterated (TMTSF) ₄ClO ₄. A possible ground state of the FISDW phase of (TMTSF) ₂C1O ₄ for various cooling rates is discussed from the viewpoint of the peculiar SDW nesting vector stabilized by the dimerized gap due to anion ordering.

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