Exchange Interactions in Heteronuclear Clusters Containing Dysprosium Ions: EPR Spectroscopy Possibility

Abstract

The exchange interaction in two isostructural compounds [M₂Dy₂ (μ₃–OH)₂(L)₂(O₂CPh–Me–p)₆] (M = Al, Cr) is studied by electron paramagnetic resonance (EPR). Studies have been performed on polycrystalline samples in different frequency ranges. The features of the shape of the spectra of clusters containing dysprosium ions are analyzed and experimental spectra are described using calculated spectra for tetranuclear clusters. The value J_zz = − 0.86 cm⁻¹ of the spin–spin interaction of the Ising form J_zzS_1zS_2z between dysprosium ions in the Al₂Dy₂ cluster, which exhibits single-molecule magnet properties, was experimentally determined. The study of the heteronuclear Cr₂Dy₂ cluster has demonstrated a number of features of the EPR spectra due to the Cr–Dy interaction. It is shown that this interaction has a predominantly Ising form with the parameter J_CrDyzz = − 1 cm⁻¹. However, the Cr–Dy pair fragment does not have a center of symmetry, and this suggests the presence of an antisymmetric term in the spin–spin interaction tensor, the manifestation of which is observed in the X-band EPR spectrum.