Hidden symmetries in Bechgaard salt (TMTSF)2NO3

Among known Bechgaard and Fabre salts (TMTSF)2NO3 is unique since it never becomes superconducting even under pressure. Also, though (TMTSF)2NO3 undergoes the spin density wave (SDW) transition, the low temperature transport is semimetallic and gapless. We propose: a) the absence of the superconductivity is due to the inverse symmetry breaking associated with the anion ordering at 45K; b) the SDW state below 9K should be unconventional as seen from the angle dependent magnetoresistance oscillation (AMRO); c) a new phase diagram for Bechgaard salts, where unconventional spin density wave (USDW) occupies the prominent space.