The field-induced transitions in a novel organic system, (DMETSeF) 2AuI 2

Abstract

We have measured magnetoresistance and Hall resistance of a novel organic conductor, (DMETSeF) 2-AuI 2. DMETSeF (dimethyl ethylene dithio tetraselena fulvalene) is a newly synthesized donor molecule. The temperature dependence of (DMETSeF) 2AuI 2 salt depends on the batch of the sample preparation. Some crystals are metallic down to 0.5 K, and the others are metallic down to 40K, but the resistivity increases with the log(T) temperature dependence from 15 K down to 0.5 K. In this material, we found a series of cascade transitions due to the magnetic field similar to the well-known FISDW (Field Induced Spin Density Wave) states in (TMTSF) 2X family. The large magnetoresistance and the period of the step-like transitions cannot be understood as the Shubnikovde Haas oscillation. The band calculation indicates 1D like Fermi surface and very similar to those of TMTSF family, therefore FISDW can be one of the candidates to understand the state. But the experimental result is somewhat different from those of TMTSF family. This result is the first field induced state in organic systems other than TMTSF family.