Dysprosium-based experimental representatives of an Ising-Heisenberg chain and a decorated Ising ring

TL;DR

This paper demonstrates that the bond-decorated Ising model accurately describes the magnetic properties of certain lanthanide-based compounds, with theoretical predictions aligning well with experimental data.

Contribution

It introduces a realistic model for lanthanide compounds using the decorated Ising chain and validates it with experimental and ab initio data.

Findings

The model accurately predicts magnetic properties of Dy-based compounds.

Agreement with experimental data is achieved after corrections for excited states.

The study clarifies the spectral similarities and differences in Ising chains.

Abstract

It is shown that the bond-decorated Ising model is a realistic model for certain real magnetic compounds containing lanthanide ions. The lanthanide ion plays the role of Ising spin. The required conditions on the crystal-field spectrum of the lanthanide ion for the model to be valid are discussed and found to be in agreement with several recent ab initio calculations on Dy(III) centers. Similarities and differences between the spectra of the simple Ising chain and the decorated Ising chain are discussed and illustrated, with attention to level crossings in a magnetic field. The magnetic properties of two actual examples (a [DyCuMoCu] chain and a Dy4Cr4 ring) are obtained by a transfer-matrix solution of the decorated Ising model. g-factors of the metal ions are directly imported from ab initio results, while exchange coupling constants are fitted to experiment. Agreement with experiment is found to be satisfactory, provided one includes a correction (from ab initio results) for susceptibility and magnetization to account for the presence of excited Kramers doublets on Dy(III).