c-axis resistivity of SbCl5 graphite intercalation compounds

The c-axis resistivity rho(c) of stage-2,3,4,5,6,7, and 9 SbCl5 graphite intercalation compounds (GICs) has been measured in the temperature range between 4.2 and 300 K with and without an external magnetic field along the c-axis. In these compounds the c-axis conduction is dominated by the in-plane conduction because of the highly anisotropic resistivity. The temperature dependence of rho(c) strongly depends on the stage number. The stage-2 and 3 SbCl5 GICs show a metallic behaviour: rho(c) increasing with increasing temperature. The logarithmic behaviour in rho(c) is observed in a limited temperature range for stages 5 and 6, and negative longitudinal magnetoresistance is observed for stages 3 to 7, indicating that the two-dimensional weak localization effect may occur mainly in the interior graphite layers with a small charge transfer. The c-axis resistivity of stage-3 to 9 SbCl5 GICs shows a unusual thermal hysteresis in the temperature range between 180 and 240 K. It has two local minima at critical temperatures T-cl (=196-210 K) and T-cu (=223-231 K) depending on the stage number. The carriers in the bounding graphite layers with a large charge transfer are scattered by enhanced fluctuations due to electric dipole moments of SbCl3 molecules. There may occur a two-dimensional-(2D-) like dipole ordered phase below T-cu and a 3D-like dipole ordered phase below T-cl.