THEORY OF THE HIGH-FIELD PHASE IN (TMTSF)(2)CLO4 UNDER ANION ORDERING

Stimulated by a recent experiment on (TMTSF)(2)ClO4, reporting a new p hase diagram with a first order transition line at the high field, the field induced spin density wave (FISDW) states are reexamined under t he anion ordering. It is found that a new type of FISDW state, which d iffers from that described by the so-called standard theory, is stabil ized. We interpret the first order line as arising from a transition b etween the new state and the standard one when H is varied.