PROPERTIES OF MOLECULAR-BASED FRUSTRATED MAGNETS

The magnetic properties of cobalt complexes of BTCA (BTCA = 1,3,5 benz enetricarboxylic acid) have been investigated. The trianion of the BTC A ligand has the ability to create lattices with competing interaction s leading to frustration. A dodecahydrate phase, Co(3)BTCA(2)(H2O)(12) , is obtained from room temperature aqueous solutions and consists of pendant chains with very small interactions. Varying the reaction cond itions leads to an amorphous phase which displays many of the features of a spin glass: hysteresis, remanent magnetization, frequency depend ent susceptibility, aging effects, and an inverse field dependence of the de susceptibility. The dehydration state and corresponding magneti c properties are strongly dependent on the temperature of the original reaction. Reaction temperatures below 78 degrees C lead to the pendan t chain while temperatures greater than 78 degrees C yield more intere sting glassy phases. These phases exhibit many properties of reentrant spin glasses.