The Effect of Ru Substitution for Ni on the Superconductivity in MgCNi3-xRux
01 January 2004
In the study reported here, we have characterized the effect of Ru substitution on the superconductivity in MgCNi3, with the goal of inducing a pure electron count effect by substitution of an electron deficient element that is not likely to act as a magnetic pair breaker due to its 4d character. Characterization of the materials prepared indicates a decrease of magnetic susceptibility with increasing Ru content, the opposite of what is observed for the Co and Mn substitutions, indicating that Ru displays no magnetic moment. Therefore the change in superconducting properties observed is expected to be primarily due to a band structure effect. We show that the superconductivity is suppressed much more slowly than is observed in the 3d element substitution cases, though again, no incipient ferromagnetic ground state is revealed.