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

TLDR

We fabricated YBa₂(Cu₀.₉A₀.₁)₃O₆₊ᵧ (A = Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn) and examined their superconducting state with resistance, magnetization, and magnetic‑susceptibility measurements above Tc. Tc was strongly correlated with the size of paramagnetic moments from magnetic sites, yet Zn substitution dramatically reduced Tc by filling the antibonding d band.

Abstract

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.