J. Phys. IV France
Volume 131, December 2005
Page(s) 269 - 272
Publié en ligne 18 janvier 2006
International Workshop on Electronic Crystals
S. Brazovskii, P. Monceau and N. Kirova
J. Phys. IV France 131 (2005) 269-272

DOI: 10.1051/jp4:2005131068

Effect of the dimerized gap due to anion ordering in the field-induced spin-density-wave of quasi-one dimensional organic conductors

N. Matsunaga1, 2, 3, K. Hino1, T. Ohta1, K. Yamashita1, K. Nomura1, T. Sasaki4, A. Ayari2, 3, P. Monceau2, 3, M. Watanabe5, J. Yamada5 and S. Nakatsuji5

1  Division of Physics, Hokkaido University, Sapporo 060-0810, Japan
2  CRTBT-CNRS, laboratoire associé à 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  IMR, Tohoku University, Sendai 980-8577, Japan
5  Department of Material Science, University of Hyogo, Kamigohri 678-1297, Japan

We have measured Hall resistance and magnetic torque in the field-induced spin-density-wave (FISDW) phase of deuterated (TMTSF)2ClO4 for various cooling rates through the anion ordering temperature. The Hall resistance with the magnetic field parallel to c* is not sensitive to cooling rate above 16 T. On the other hand, the Hall resistance between 9 and 14 T rapidly and continuously decreases with increasing cooling rate. This result means that the Hall resistance in the semimetallic SDW phase between 9 and 14 T is not quantized in the intermediate cooled states. A new phase transition from the non-quantized phase to the quantized (n=1) Hall phase exists with hysteresis of the Hall resistance. Moreover, the new phase boundary is shifted towards a lower field when the cooling rate is increased. We have also found that the magnetic torque in the non-quantized phase rapidly decreases with increasing cooling rate. A possible ground state of non-quantized and Hall phase of the FISDW phase of (TMTSF)2ClO4 is discussed from the viewpoint of the peculiar SDW nesting vector.

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