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. Matsunaga^{1, 2, 3}, K. Hino¹, T. Ohta¹, K. Yamashita¹, K. Nomura¹, T. Sasaki⁴, A. Ayari^{2, 3}, P. Monceau^{2, 3}, M. Watanabe⁵, J. Yamada⁵ and S. Nakatsuji<sup>5

1</sup>  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

Abstract
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.

© EDP Sciences 2005