Effect of Pr substitution on competition between magnetism and superconductivity in RuGd1.5Ce0.5-xPrxSr2Cu2O10 (Ru-1222) rutheno-cuprate compounds

Full text: The general antagonism nature between superconductivity and long range magnetic order is one of the fundamental problems of condensed matter physics. We have prepared RuGd1.5Ce0.5-xPrxSr2Cu2O10 compounds with 0<x<0.1 by the standard solid-state reaction method in order to determine the role of Pr substitution for Ce ions in these magnetic-superconducting-layered cuprate systems. The structural studies by powder X-ray diffraction measurements and Rietveld refinement, confirm the purity of the phase of the samples. The electrical resistivity and magnetoresistance (0-1.5T) vs temperature measurements for different amounts of x have been performed. The systems become antiferromagnetic ordered at Tm which varies with increasing Pr substitution for Ce from approximately 178K for x=0 to 116K for x=0.1. Weak ferromagnetic state is induced by the canting of the Ru moments at Tirr, which shifts by Pr content from 154K to 54K for x=0, x=0.1 respectively. These may be caused by the magnetic properties of Pr ions and its different valance and radii in the structures in comparison with the Ce ions, which affects the oxygen content of the material, that could influence on the Ru-Ru interaction. The samples become superconductor at Tc, which decreases from 39K for x=0 to lower temperatures with increasing Pr content. The magnetic features are not affected by the presence of the superconducting state, and the two states coexist. Magnetization parameters such as Msat, Mrem and Hc are obtained by magnetization measurements under magnetic field of 2T at isotermic 77K and room temperature via a vibrating sample magnetometer. Irreversible hysteresis loops confirmed the existence of ferromagnetic phase in the compositions. (authors)