Electron paramagnetic resonance [Cu³⁺–Cu²⁺](C_2v) impurity dimers in BaF₂:Cu ionic crystal

Impurity dimers [Cu³⁺–Cu²⁺] (С_2v) with an antiferromagnetic bond between copper ions have been synthesized in BaF₂ crystals. The study of the molecular structure of the synthesized dimers was carried out by the electron paramagnetic resonance at frequencies of 9.3 and 34.2 GHz in the temperature range from 5 to 150 K. It was shown that the ⁶³Cu³⁺ and ⁶³Cu²⁺ ions replaced the neighboring cations of the Ва²⁺ lattice, forming a dimer with a parallel bond axis of one of the 〈110〉 crystallographic axes. It has been found that the coupling between copper ions has an antiferromagnetic exchange interaction and that its repeated inverse state is a doublet, S = 1/2. There were determined parameters of Zeeman interaction, part of the parameters of the hyperfine and quadrupole interaction of ⁶³Cu³⁺ and ⁶³Cu²⁺ ions, as well as part of the parameters of the ligand hyperfine interaction with two equivalent F^– ions.