Magnetic structure and phase transitions in the “green phase” 160Gd2BaCuO5: Neutron diffraction study

By powder neutron diffraction on an isotopically substituted 160Gd2BaCuO5 sample we observed an incommensurate magnetic structure with a propagation vector k=[001/2−δ] below 12 K. A “lock-in” to a commensurate structure with k=[0 0 1/2] propagation vector occurs at 5 K accompanied with a spin re-orientation in the Gd subsystem and a magnetostructural transition. The temperature dependence of the Gd moments suggests a low dimensional behaviour similar to that found in other rare-earth cuprates.