Quasi-one-dimensional Fermi surface of (TMTSF)₂NO₃

Stereoscopic angular dependence of the interlayer magnetoresistance of the Bechgaard salt (TMTSF) 2 NO3 is investigated under pressure. This compound is believed to be a semimetal having the quasi-two-dimensional Fermi surface (FS) at low temperature. Previously, a field-induced spin-density-wave (FISDW) transition was reported at 8.5 kbar above ∼20 T, which is atypical with a closed FS. We present strong evidence that the FS of this compound remains quasi-one-dimensional under moderate pressure even in the presence of anion ordering. The occurrence of the FISDW is therefore unsurprising. In addition, the possibility of an anion ordering along the b axis will be discussed.