Antiferromagnetic ordering in the organic conductor bis-tetramethyltetraselenafulvalene-hexafluorophosphate [(TMTSF)2 -PF6]

The anisotropy in the static susceptibility of (TMTSF)2-PF6 has been investigated above and below the metal-insulator transition for a range of fields between 4 and 25 kOe. The results are consistent with the occurrence of an Overhauser antiferromagnetic transition to a spin-density-wave state with an easiest axis perpendicular to the stacks. Below the transition, evidence for a spin-flop transition is seen. Above the transition, evidence for a crossover, possibly from n=3 to n=1 spin behavior, is seen. © 1981 The American Physical Society.