CHARACTERIZATION OF THE FERMI-SURFACE OF THE ORGANIC SUPERCONDUCTOR BETA''-(ET)(2)SF5CH2CF2SO3 BY MEASUREMENTS OF HAAS,SHUBNIKOV,DE AND ANGLE-DEPENDENT MAGNETORESISTANCE OSCILLATIONS AND BY ELECTRONIC BAND-STRUCTURE CALCULATIONS

The electronic structure of the quasi two-dimensional (2D) organic sup erconductor beta ''-(ET)(2)SF5CH2CF2SO3 was examined by measuring Shub nikov-de Haas (SdH) and angle-dependent magnetoresistance (AMRO) oscil lations and by comparing with electronic band-structure calculations. The SdH oscillation frequencies follow the 1/cos theta angular depende nce expected for a 2D Fermi surface (FS), and the observed fundamental frequency shows that the 2D FS is 5% of the first Brillouin zone in s ize. The AMRO data indicate that the shape of the 2D FS is significant ly non-circular. The calculated electronic structure has a 2D FS in ge neral agreement with experiment. From the temperature and angular depe ndence of the SdH amplitude, the cyclotron and band effective masses w ere estimated to be m(c) = (1.9 +/- 0.05)m(e) and m(b) = (3.90+/-0.05) m(e)/g, where g is the conduction electron g factor and m(e) the free electron mass. The band effective mass is estimated to be m(b)' =1.07 m(e) from the calculated electronic band structure.