NONLINEAR MAGNETIC RESPONSE AT THE CRITICAL POINTS OF GRAPHITE COMPOUNDS INTERCALATED BY TRANSITION METAL CHLORIDES

Ordering of CoCl2−, NiC12− and CrCl3−graphite intercalation compounds (GIC) is studied by observing nonlinear magnetic response at weak AC excitation fields and at very low frequencies. The result for CoCl2− and NiCl2−GICs supports the two-step hierarchical spin ordering model by confirming the non-breaking of total magnetic symmetry between the upper and lower transition temperatures.