Andrew Boothroyd

Abstract:

We report the discovery of incommensurate magnetic order in non-superconducting single crystals PrBa2Cu3O6.92. Resonant X-ray magnetic scattering at the Pr L-II and L-III edges and high resolution neutron diffraction were used to characterise the magnetic order on the different magnetic sublattices. The data reveal that the Pr sublattice orders at a temperature of 19 K in an incommensurate structure with ordering wavevector (0.5 +/- delta, 0.5, 0) or (0.5, 0.5 +/- delta, 0), delta approximate to 0.006-0.008, A spin reorientation in the Pr sublattice to a commensurate antiferromagnetic structure with ordering wavevector (0.5, 0.5, 0.5) takes place at a temperature close to 9 K. (C) 1999 Elsevier Science B.V. All rights reserved.

Abstract:

Inelastic neutron scattering measurements have been performed, for the first time, on a large, high quality single-crystal of PrBa2Cu3O6+x. Two relatively broad peaks are observed, the one at lower energy showing significant dispersion in the basal plane. Neither feature is observable above the Pr ordering temperature. The pressure dependence of the Cu and Pr ordering temperatures up to 1.75 GPa has also been determined. (C) 1999 Elsevier Science B.V. All rights reserved.