Scattering phase shifts in Ni and Zn doped Y-123

Effect of anisotropic impurity scattering in superconductors

“…As the impurity scattering strength is rather impossible to be determined from first principles, the information about the scattering process is usually deduced from a comparison of the experimental data with the theoretical models. These models assume a certain phenomenological impurity potential 23,24,29,30,[32][33][34][35][36] which is verified by a fit to the available data. We proceed in the same way by analyzing the impurity scattering potential of the factorizable form…”

Suppression of superconductivity in high- cuprates due to nonmagnetic impurities: Implications for the order parameter symmetry

“…• For YBa 2 (Cu 1−x Zn x ) 3 O 7−δ compounds, at small concentrations, x < 0.04, Zn ions occupy preferably Cu-sites in the CuO 2 planes, however for x > 0.04 the substituent starts to occupy Cu-sites in the chain 16,19,[45][46][47] . Since this compound has two planes and one chain in a unit cell, for x < 0.04 the actual (effective) impurity concentration n i , i. e. the number of impurities per unit cell per CuO 2 plane, becomes 3x/2.…”

“…In comparing our results with experimental data we should keep the following point in our mind. For x < 0.04, substitutional impurities go to preferentially CuO 2 planes 16,19,[45][46][47] and hence the actual concentration is 3x/2. However for higher concentrations some of the Zn atoms occupy the chain sites, and in this case we can not relate the in plane concentration to the actual one.…”