ANTIFERROMAGNETIC ORDER OF CU2+ SPINS AND STRUCTURAL FLUCTUATIONS IN BI2SR2PRCU2O8+DELTA

Using neutron scattering we have investigated the magnetic correlation s in single crystals of the Bi-2212 phase, fully praseodymium-substitu ted for Ca according to the nominal composition Bi2Sr2PrCu2O8+delta. B y means of this substitution the system is shifted to the non-supercon ducting limit. We have shown, in addition to a Bbmb-Fmmm structural ph ase transition, the existence of long-range, three-dimensional, antife rromagnetic ordering of the Cu2+ spins below a Neel temperature T-N si milar to 350 K. A model for the magnetic structure is proposed and com pared to the experimental data. Additional weakly correlated two-dimen sional structural fluctuations are also observed.