Superconductivity and field induced states in DMET-TSeF family

Summary form only given. The magnetoresistance and magnetization measurements have been performed in (DMET-TSeF)/sub 2/X (X= AuI/sub 2/, AuBr/sub 2/, AuCl/sub 2/, Au(CN)/sub 2/, and I/sub 3/ .) family. All of them have quasi one-dimensional Fermi surfaces at room temperature. It has been found that two of them(X= AuI/sub 2/ and I/sub 3/) show superconductivity at ambient pressure below I K. It has been also found that AuI/sub 2/, AuBr/sub 2/, and AuCl/sub 2/ salts show the Field Induced Spin Density Wave(FISDW), AuI/sub 2/ and Aul/sub 2/ at ambient pressure and AuBr/sub 2/ under pressure. The observed magnetization oscillations are smaller than those observed in (TMTSF)/sub 2/CIO/sub 4/. We did not observe any magnetoresistance oscillation in superconducting I/sub 3/ salt up to 12 T. The Au(CN)/sub 2/ salt shows Shubnikov-de Haas oscillation indicating closed Fermi surface at the lowest temperature.