Hyperfine Interaction of Cu Nuclei in the Mixed System (CH₃NH₃)₂Cu(Cl_1−xBr_x)₄

Abstract

The hyperfine field of Cu nuclei has been investigated theoretically with the use of the molecular orbitals for the cluster of central Cu²⁺ ion and the surrounding ligands. According to the previous experimental studies, the hyperfine field of Cu nuclei as well as the g-factors vary linearly with n, the number of Br⁻ ions in the surrounding ligand sites. Such linear dependences have been reasonably explained and have turned out to be due to the difference between the unpaired spin densities of Cl⁻ and Br⁻ ions as well as the difference between the overlap integrals of Cu²⁺–Cl⁻ and Cu²⁺–Br⁻ ions.