Superconducting and normal-state properties of ${\mathrm{YBa}}_2$(${\mathrm{Cu}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Zn}}_{\mathit{x}}$${)}_4$${\mathrm{O}}_8$

We investigate the effect of Zn substitution for Cu on the lattice parameters and the temperature dependences of resistivity and susceptibility in ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_4$ ${\mathrm{O}}_8$. Samples of ${\mathrm{YBa}}_2$(${\mathrm{Cu}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Zn}}_{\mathit{x}}$ ${)}_4$ ${\mathrm{O}}_8$ with x=0 to 0.1 were prepared by a high-oxygen-pressure technique. As the Zn context is increased, the lattice parameters of the a and b axes increase, but that of the c axis decreases. The oxygen content is independent of the Zn concentration. The superconducting transition temperature ${\mathit{T}}_{\mathit{c}}$ decreases monotonically with increasing Zn concentration, with a coefficient of -21 K/at.%, and superconductivity vanishes at x=0.037. The Zn doping induces the local moment coming from ${\mathrm{Cu}}^{2+}$, and the normal-state susceptibility shows Curie-Weiss-like behavior. Some possible explanations for the suppression of ${\mathit{T}}_{\mathit{c}}$ by Zn doping are provided.