Hyperfine Interactions in Copper Lattice Sites of Antiferromagnetic Compounds Representing the Analogues of Superconducting Copper Metal-Oxide Compounds

Emission ⁶¹Cu(⁶¹Ni) Mössbauer spectra of dielectric metal-oxide compounds of divalent copper with molecular formulas Ca_1 – xSr_xCuO₂, Ca₂CuO₂Cl₂, SrCuO₂, Sr₂CuO₂Cl₂, YBa₂Cu₃O_7 – x, La_2 – xSr_xCuO₄, and Nd_2 – xCe_xCuO₄ correspond to the quadrupole and Zeeman interactions of the ⁶¹Ni nuclei with local fields at the copper lattice sites, whereas the spectra of superconducting metal-oxide complexes correspond to the interaction of the quadrupole moment of the ⁶¹Ni nuclei with the tensor of the electric field gradient (EFG). For both groups of metal oxides, linear dependences of the quadrupole interaction constants on the calculated values of the principal component of the lattice EFG tensor in the copper lattice sites are observed both on the ⁶¹Ni nuclei (data of the emission Mössbauer spectroscopy on the ⁶¹Cu(⁶¹Ni) isotopes) and on the ⁶³Cu nuclei (data of the nuclear magnetic resonance on the ⁶³Cu isotope). This fact is explained by the constant values of the valence component of the EFG for both the ⁶¹Ni²⁺ and ⁶³Cu²⁺ probes in all metal-oxide complexes of divalent copper.