MAGNETIC-PROPERTIES OF RANDOM-MIXTURE GRAPHITE-INTERCALATION COMPOUNDS

Random-mixture GICs such as stage-2 NicMn1-cCl2 GICs and stage-2 CocMn 1-cCl2 GICs provide model systems for studying 2D random spin systems with spin frustration effects. The magnetic properties of these compou nds have been studied by de and ac magnetic susceptibility, and low fi eld SQUID magnetization measurements. An irreversible effect of magnet ization for stage-2 NicMn1-cCl2 GICs (0.8 less than or equal to c less than or equal to 1) and stage-2 CocNi1-cCl2 GICs (0 less than or equa l to c less than or equal to 1) indicates an occurrence of cluster gla ss phase below a critical temperature where the spin directions of fer romagnetic clusters are frozen because of frustrated inter-island inte ractions.