Effect of Nonmagnetic Ion Lu Substitution for Dy on Superconductivity and Magnetism in Antiferromagnetic Superconductor Dy1-xLuxNi2B2C Compound
A series of Dy1-xLuxNi2B2C (x=0--1) compounds have been investigated by X-ray diffraction and by examining the temperature dependences of electrical resistivity, magnetization and heat capacity. All the samples exhibit the same LuNi2B2C-type structure; and lattice parameters depend almost linearly on the Lu concentration x. The superconducting transition temperature Tc decreases rapidly with increasing x, and superconductivity disappears at approximately x=0.2, then increases with a further increase in x. The magnetic transition temperature TM and the effective magnetic moment Peff decrease gradually with increasing x. The ferrimagnetic-like behavior emerges at about x=0.2; which can be the main reason causing the suppression of superconductivity. The temperature dependence of the magnetic entropy Sm originated from Dy ions has been evaluated on the basis of heat capacity data. The saturated values of Sm(T)/(1-x) are approximately 90% of R\ln 4 and the effective magnetic moment normalized by Dy concentration is almost unchanged, which indicates that the magnetic ground state of Dy3+ does not show a pronounced change.