Role of the dimerized gap due to anion ordering in spin-density wave phase of (TMTSF)2ClO4 at high magnetic fields -: art. no. 024425

Magnetoresistance measurements have been carried out along the highly conducting a axis in the field-induced spin-density wave (FISDW) phase of hydrogenated and deuterated (TMTSF)(2)ClO4 for various cooling rates through the anion ordering temperature. With increasing the cooling rate, (i) the high-field phase boundary beta(HI), observed at 27 T in hydrogenated samples for slowly cooled, is shifted towards a lower field, (ii) the last semimetallic SDW phase below beta(HI) is suppressed, and (iii) the FISDW insulating phase above beta(HI) is enhanced in both salts. The cooling rate dependence of the FISDW transition and of beta(HI) in both salts can be explained by taking into account the peculiar SDW nesting vector stabilized by the dimerized gap due to anion ordering.