Investigations of Knight shifts and g factors for Y123 and Y124 superconductors

Highlights: • We study g factors and Knight shifts for Y123 and Y124 superconductors. • The theoretical relationships between Knight shifts and g factors are established. • High order perturbation formulas are adopted with local structures of Cu2+ sites. • Anisotropies of g factors and Knight shifts are ascribed to elongation of Cu2+ sites. -- Abstract: By adopting the uniform high order perturbation formulas of Knight shifts and g factors for 3d9 ions in orthorhombically and tetragonally elongated octahedra, the experimental results of these parameters for Cu(1) sites in YBa2Cu3O7, YBa2Cu3O7−σ and YBa2Cu4O8 and Cu(2) site in YBa2Cu3O7−σ are systematically investigated. The calculated Knight shifts (and g factors for Cu(2) site) agree well with the observed values. The anisotropies of the g factors and Knight shifts are attributed to the local orthorhombic and tetragonal elongations of the Cu2+ sites. The present studies would be helpful to attain a more complete spectroscopic understanding for g factors and Knight shifts