Neutron and X-ray scattering studies of magnetism in non-superconducting PrBa2Cu3O6+x

I give a short review of neutron and X-ray scattering experiments undertake n to study the magnetic properties of non-superconducting PrBa2Cu3O6+x. The measurements have confirmed the magnetic ordering of the Pr sublattice at temperatures below T-Pr approximate to 20 K, and have revealed an incommens urate magnetic structure with a long period (similar to 600 Angstrom) invol ving both the Pr and Cu spins. The Cu spins in this Pr ordered phase are fo und to be non-collinear. Taken as a whole, the results provide strong evide nce for a substantial magnetic coupling of the pseudodipolar type between t he Pr and Cu ions. The effect of this coupling is also evident in the spect rum of low energy magnetic excitations determined by neutron inelastic scat tering. (C) 2000 Elsevier Science S.A. All rights reserved.