Magnetothermal Oscillations in Graphite Intercalation Compounds.

The Fermi surface (FS) of SbCl(,5)-GIC's for stage 1 to stage 8 has been studied using the magnetothermal oscillation method. The majority of the measurements were performed at about 1K and in magnetic fields up to 5T (50kG). Frequencies of the dHvA oscillations were determined by a fast Fourier transform analysis of the raw data, using an on-line computer. The results show a monotonic increase in the area of the FS with decreasing stage index and a weak monotonic increase of the charge transfer coefficient, f, with increasing stage index. The shape of the FS, as deduced from the angle dependence of the frequencies, is consistent with a cylindrical surface or an elongated ellipsoidal one. For the stage 6 sample we have also determined the effective mass of the carriers in the plane perpendicular to the c-axis, and find that m* = 0.3 m(,o), in agreement with calculated masses based on the Slonczewski-Weiss-McClure (SWMcC) model of the band structure of graphite. Our results are in good agreement with a model for the band structure of GIC's based on the rigid band model (RBM) when zone folding along the c-axis is employed.