Theory of reentrance of spin-density-wave transitions in bis-tetramethyltetraselenafulvalenium perchlorate [(TMTSF)2ClO4]

The stability of spin-density-wave formation in the organic superconductor bis-tetramethyltetraselenafulvalenium perchlorate (TMTSF${)}_2$ ${\mathrm{ClO}}_4$ is studied. The anion gap in the electron spectrum causes reentrance of the metallic state in high magnetic fields. It also leads to fast oscillations of physical properties, in particular, the phase-transition temperature versus magnetic field. Both these phenomena have been observed experimentally.