The effect of chemical pressure in rutheno-cuprates

We have studied the effect of negative chemical pressure in the RuGd1.5(Ce0.5−xPrx)Sr2Cu2O10−δ with Pr content of 0.0 ⩽ x ⩽ 0.2. This is also investigated using the bond length results obtained from the Rietveld refinement analysis. The c parameter and cell volume increase with x for 0.0 ⩽ x ⩽ 0.15. The width of the resistivity transition also increases with Pr concentration, indicating higher inhomogeneity and oxygen deficiency. The difference in the ionic valences of Pr3+,4+ and Ce4+ causing different hole doping, the difference in the ionic radii, and oxygen stoichiometry affect the superconducting transition. The magnetoresistance shows a cusp around 135 K which lies between the antiferromagnetic and ferromagnetic transition temperatures, which is probably due to the presence of a spin glass region. There exist two magnetic transition temperatures for 0.0 ⩽ x ⩽ 0.2 which respectively change from TM = 155 K to 144 K and from Tirr = 115 K to 70 K. The magnetization versus applied magnetic field isotherms at 77 K and 300 K show that the remanent magnetization and coercivity are lower for samples with higher Pr content.