Perylene hexafluoroantimonate: Suppression of the Peierls transition by anion-chain disorder

Crystal growth and X-ray structural analysis are reported for the new quasi -one-dimensional; organic conductor perylene hexafluoroantimonate. Due to d eviation from exact 4:3 stoichiometry and anion-chain disorder the three-di mensional Peierls transition is suppressed to temperatures below 30 K in sp ite of a molecular field transition temperature of 330 K. Anisotropy of the microwave conductivity exceeds 3000:1 at room temperature. Curie paramagne tic defects with comparatively small electron spin resonance line width pre dominate at low temperature. Thermally activated paramagnetic defects, givi ng rise to pronounced Overhauser shift, are separated in the 30-100 K range . They are explained by neutral Perylene intra-stack defects, whose concent ration can be reduced by both aging and annealing. The angular and temperat ure dependence of the conduction electron spin resonance line is analysed i n detail, exhibiting the influence of intra-stack dipole interaction growin g with temperature. Restricted diffusion of the conduction electron spins w ith diffusion coefficient of about 6 cm(2)/s parallel to the stacking direc tion is detected by fixed gradient pulsed electron spin resonance at room t emperature.