EPR AND MAGNETIC MEASUREMENTS OF BACUO2+X

We have obtained several samples of BaCuO2+x in powder and single crys talline forms, for which we have performed studies of structural, magn etic and EPR properties. The magnetic properties of this oxide are mai nly associated with the two kinds of very well isolated Cu2+ ion clust ers. The magnetization curve and the EPR results at low temperatures s uggest the presence of ferromagnetically correlated spins. The exchang e parameter, J/k(B), was found to be about 100 K, although no evidence of long-range magnetic ordering has been noted down to 4.2 K in our m easurements. Instead, the low temperature EPR and DC-susceptibility re sults strongly suggest a spin-glass behavior.