Fe-Gd Ferromagnetic Cyclic Coordination Cluster [FeIII4GdIII4(teaH)8(N3)8(H2O)] with Magnetic Anisotropy-Theory and Experiment

The synthesis, structural, and magnetic characterization of [FeIII4LnIII4(teaH)8(N3)8(H2O)] (Ln = Gd and Y) and the previously reported isostructural Dy analogue are discussed. The commonly held belief that both FeIII and GdIII can be regarded as isotropic ions is shown to be an oversimplification. This conclusion is derived from the magnetic data for the YIII analogue in terms of the zero-field splitting seen for FeIII and from the fact that the magnetic data for the new GdIII analogue can only be fit employing an additional anisotropy term for the GdIII ions. Furthermore, the Fe4Gd4 ring shows slow relaxation of magnetization. Our analysis of the experimental magnetic data employs both density functional theory as well as the finite-temperature Lanczos method which finally enables us to provide an almost perfect fit of magnetocaloric properties.

Automated summary

The synthesis, structural, and magnetic properties of [FeIII4LnIII4(teaH)8(N3)8(H2O)] (Ln = Gd and Y) and its Dy analogue are discussed. The oversimplification of considering both FeIII and GdIII as isotropic ions is shown through magnetic data analysis. The Fe4Gd4 ring exhibits slow magnetization relaxation, and the magnetocaloric properties are well described by density functional theory and the finite-temperature Lanczos method.