Fermiology of the organic superconductor beta ''-(ET)(2)SF5CH2CF2SO3

We present a detailed Fermi-surface (FS) investigation of the quasi two-dim ensional (2D) organic superconductor (T-c = 4.5 K) beta "-(ET)(2)SF5CH2CF2S O3. In line with previous investigations, de Haas-van Alphen measurements i n pulsed fields up to 60 T show a single oscillation frequency, F-0 = 200 T , which corresponds to a FS size of about 5% of the first Brillouin zone. A ngular dependent magnetoresistance oscillations (AMROs) are utilized for th e exact determination of the in-plane FS, which is found to be a strongly e longated ellipsoid with an axes ratio of about 1:9. Transport measurements in static fields up to 33 T show an unusual temperature dependence of the S hubnikov-de Haas (SdH) signal, i.e., a decrease of the SdH amplitude with d ecreasing temperature.