Magnetoresistance of the second-stage NiCl 2-, CoCl 2- and CuCl 2-graphite intercalation compounds

Abstract

The magnetoresistance of the second-stage graphite intercalation compounds of MCl 2 has been measured in the temperature range 1.4 – 30 K and in magnetic fields up to 10 kOe. Here, M is one of Ni, Co or Cu, and the host material is single-crystal (KISH) graphite. All the compounds showed a negative magnetoresistance, whose minimum is distributed around a few hundred Oe. The existence of negative magnetoresistance suggests a considerable contribution of the magnetic scattering from the intercalants to the conduction electrons. It has been concluded that the dominant origins of the negative magnetoresistance come from the suppression of magnon or spin disorder scattering by the magnetic field, and/or from the spin flop process. The competition between the different anisotropy of effective fields, the different transition temperatures and the different spin flop fields gives rise to a variety of behaviours in different samples.