Substitution for Cu in the electron-doped infinite-layer superconductor ${\mathrm{Sr}}_{0.9}{\mathrm{La}}_{0.1}{\mathrm{CuO}}_2:$ Ni reduces $T_c$ much faster than Zn

We have substituted magnetic Ni and nonmagnetic Zn impurities at Cu sites, in order to probe the nature of the superconductivity for the electron-doped infinite-layer superconductor ${\mathrm{Sr}}_{0.9}{\mathrm{La}}_{0.1}{\mathrm{CuO}}_2.$ We found that $T_c$ was nearly constant until 3% replacement by Zn while the superconductivity was nearly suppressed for a 2% substitution by Ni. This behavior is very similar to that of conventional superconductors, but quite different from typical holed-doped cuprate superconductors.