Comparing the physical properties of Pr/Gd and Pr/Ce substitutions in Ru(Gd1.5Ce0.5)Sr2Cu2O10-δ
Magnet Research Laboratory (MRL), Department of Physics, Sharif University of Technology, PO Box 11365-9161, Tehran, Iran
Corresponding author: a firstname.lastname@example.org
Revised: 18 January 2008
Published online: 10 July 2008
We have compared the electrical and magnetic properties of Ru(Gd1.5-xPrx)Ce0.5Sr2Cu2O10-δ (Pr/Gd samples) with x = 0.0, 0.01, 0.03, 0.033, 0.035, 0.04, 0.05, 0.06, 0.1 and RuGd1.5(Ce0.5-x Prx) Sr2 Cu2O10-δ (Pr/Ce samples) with x = 0.0, 0.01, 0.03, 0.05, 0.08, 0.1, 0.15, 0.2 prepared by the standard solid-state reaction technique. We obtained the XRD patterns for different samples with various x. The lattice parameters versus x for different substitutions have been obtained from Rietveld analysis. To determine how the magnetic and superconducting properties of these layered cuprate systems can be affected by Pr substitution, the resistivity, and magnetoresistivity, with Hext varying from 0.0 to 15 kOe, have been measured at various temperatures. Superconducting transition temperature Tc and magnetic transition Tirr, have been obtained through resistivity and ac susceptibility measurements. The Tc suppression due to Pr/Gd and Pr/Ce substitutions show competition between pair breaking by magnetic impurities, hole doping due to different valances of ions, difference in ionic radii, and oxygen stoichiometry. Pr/Gd substitution suppresses superconductivity more rapidly than for Pr/Ce, showing that the effect of hole doping and magnetic impurity pair breaking is stronger than the difference in ionic radii. In Pr/Gd substitution, the small difference between the ionic radii of Pr3+,4+ and Gd3+, and absorption of more oxygen due to the higher valence of Pr with respect to Gd, decreases the mean Ru–Ru distance, and as a result, the magnetic exchange interaction becomes stronger with the increase of x. However, Pr/Ce substitution has the opposite effect. The magnetic parameters such as Hc, obtained through magnetization measurements versus applied magnetic field isotherm at 77 K and room temperatures, become stronger with x in Pr/Gd and weaker with x in Pr/Ce substitution.
PACS: 74.25.Ha – Magnetic properties / 74.25.Fy – Transport properties / 74.70.Pq – Ruthenates
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008