Electron paramagnetic resonance and magnetic susceptibility of rare-earth hydrazone compounds

The magnetic properties of the rare earth molecular compounds with hydrazone ligands containing Nd3+, Gd3+, and Yb3+ have been investigated by electron paramagnetic resonance (EPR) and magnetization measurements. For the Gd-compound, partially resolved fine structure due to Gd3+ and exchange narrowing effects at low temperatures are observed in the EPR spectra, suggesting, consistent with the EPR and dc magnetic susceptibility, weak antiferromagnetic exchange interactions. Paramagnetic behavior sustained down to low temperatures is derived for Yb3+ ions, whereas substantial ferromagnetic exchange coupling is inferred for the lighter Nd3+ ions, indicating significant variations of the exchange integrals along the lanthanide series. (authors)