Effect of transition-metal elements on the superconductivity of Y-Ba-Cu-O

We have fabricated samples of the form ${\mathrm{YBa}}_{2}$(${\mathrm{Cu}}_{0.9}$${\mathrm{A}}_{0.1}$${)}_{3}$${\mathrm{O}}_{6+\mathrm{y}}$ where A=Ti, Cr, Mn, Fe, Co, Ni, Cu, and Zn. The superconducting state was investigated by both resistance and magnetization measurements. In addition, the magnetic susceptibility above ${T}_{c}$ has been measured. ${T}_{c}$ was found to be strongly correlated with the size of the paramagnetic moments, largely due to scattering from the magnetic sites. In the sample containing Zn, however, ${T}_{c}$ was dramatically reduced due to filling of the antibonding d band.