Electric and magnetic properties of the stage-2 FeBr2 graphite intercalation compound

The stage-2 FeBr2 graphite intercalation compound (GIC) was prepared by reacting FeBr2 powder and highly oriented pyrolytic graphite in a bromine atmosphere at 500degreesC for 40 weeks. The dc magnetization, ac susceptibility, specific heat, resistivity and Hall effect were measured. The GIC is paramagnetic at temperatures above 14.5 K. There is short-range ordering at 14.5 K and longer-range magnetic ordering at 8.5 K. There is a spin glass phase below 3.2 K in which the ac susceptibility is frequency dependent. The in-plane and c-axis resistivities result from in-plane and out-of-plane electron-phonon scattering. The Hall coefficient is independent of temperature between 4.2 and 300 K and is explained by the single-carrier model.