SPIN ARRANGEMENTS IN CDCR2(1-X)IN2XS4-TYPE INSULATING REENTRANT COMPOUNDS

The spinel solid solutions CdCr2(1-x)In2xS4 have been studied both by means of macroscopic magnetization measurements and by neutron diffrac tion in the dilution range 0 less than or equal to x less than or equa l to 0.10. The dramatic effect of frustration is evidenced, which lead s to the disappearance of the ferromagnetic long-range order for 10% d ilution. The x = 0.05 compound exhibits the characteristic features of re-entrance, but with a clear difference from metallic re-entrant sys tems. A qualitative 'local mean-field' model is proposed, which stress es the relevance of the range of the magnetic interaction.