Tuning Electronic Ground States by Using Chemical Pressure on Quasi-Two Dimensional beta'- (BEDT-TTF)4 [(H3O)M(C2O4)3]

• Published in: Journal of low temperature physics 2006-02, Vol.142 (3-4), p.253-256
• Main Authors: Colde, A I, Bangur, A F, Singleton, J, Ardavan, A, Akutsu-Sato, A, Akutsu, H, Day, P
• Format: Article
• Language: English
• ISSN: 0022-2291
• DOI: 10.1007/s10909-006-9196-6

We report high-field magnetotransport studies on quasi-two dimensional ff'- (BED T- TTF)41(1130)M (C204)3PY where Y is a solvent in the anionic layer. By changing the size of the solvent the low temperatures electronic behaviour varies from superconducting (for larger solvents, Y=C6H5NO2 and C6H5CN) to metallic (for smaller solvents, Y=C5H5N and CH2a2). These changes in the ground state are connected with modifications of the Fermi surface, which varies from having one or two pockets for the superconducting charge-transfer salts to at least four pockets in the case of metallic ones. When superconducting, the materials have very large in-plane critical fields (up to 32 T) and enhanced effective masses compared with the metallic compounds. The role of the charge-order fluctuations in stabilizing the superconducting ground state and the effects of intrinsic local disorder is discussed.