Poster Presentation The 35th Biennial Conference of the Society of Crystallographers in Australia and New Zealand 2024 (Crystal 35)

Angle and distance dependence of magnetic exchange interaction via selenite bridges in copper dimer units (#108)

Artem Moskin 1
  1. School of Chemistry, Faculty of Science, The University of Sydney, Sydney, New South Wales, Australia

Nowadays, many systems with the super-superexcange through several orbitals of chemically connected ligand groups were published. For example, the copper phosphates and selenites possess strong correlations with the exchange interactions exceeding 100 K[1]. The superexchange interaction through the orbitals of one nonmagnetic atom can be predicted quite well with the Goodenough-Kanamori-Anderson rules. Other interactions were neglected and were always out of the scope. The aim of our research was to understand the influence of the ligand rotation on the magnetic exchange interaction in the copper compounds. Due to the small amount of crystal structures with the known parameters of superexchange interaction, the computational DFT method was used. For the calculations of magnetic excnahge interaction, the ORCA software was used with the B3LYP functional and DKH-def2-TZVP basis sets. As the ideal body was used, the system (SeO3)2-(CuO4Cl2)-(SeO3)2-(CuO4Cl2)-(SeO3)2 is formed by two copper octahedrons linked by two selenite groups with four terminal selenite groups. The intrinsic angles and distances of the selenite group and the copper octahedra were fixed, and the relative angle was changed via rotational transformation. As a result, the angular dependence of the magnetic super-superexchange interaction was obtained for the series of 3 rotations. The most prominent dependence was obtained with the rotation of the selenite group around the axis of linking oxygens: at a plain parallel configuration, the system possesses the ferromagnetic exchange interaction. The analysis revealed two magic points at -33 and +14 degrees where the system cancels out any magnetic interaction, and below -33 degrees the system becomes an antiferromagnetic one. 

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