Investigations on the spin Hamiltonian parameters of Cu(2) site in (Tl0.5Pb0.5)Sr2CaCu2O7 superconductors

Abstract

The spin Hamiltonian parameters ([Formula: see text] factors and hyperfine structure constants) of the five-fold coordinated Cu(2) site in [Formula: see text] superconductors are investigated from the high order perturbation formulas of these parameters for a [Formula: see text] ion in tetragonally elongated octahedron. The observed anisotropies [Formula: see text] and [Formula: see text] are ascribed to the [Formula: see text] ground state for [Formula: see text] under octahedral tetragonal elongation distortion. The comparable magnitudes of the parallel and perpendicular hyperfine structure constants may be illustrated by the small core polarization constant and the reduction factor [Formula: see text]. The ligand orbital and spin–orbit coupling contributions are found to be important due to significant covalency and should be considered in the calculations.