Multi-Technique Experimental Benchmarking of the Local Magnetic Anisotropy of a Cobalt(II) Single-Ion Magnet.

A comprehensive understanding of the ligand field and its influence on the degeneracy and population of -orbitals in a specific coordination environment are crucial for the rational design and enhancement of magnetic anisotropy of single-ion magnets (SIMs). Herein, we report the synthesis and comprehensive magnetic characterization of a highly anisotropic Co SIM, [LCo](TBA) (L is an ,'-chelating oxanilido ligand), that is stable under ambient conditions. Dynamic magnetization measurements show that this SIM exhibits a large energy barrier to spin reversal > 300 K and magnetic blocking up to 3.

Influence of pressure on a dysprosocenium single-molecule magnet.

The effects of external pressure on a high-performing dysprosocenium single-molecule magnet are investigated using a combination of X-ray diffraction, magnetometry and theoretical calculations. The effective energy barrier () decreases from 1300 cm at ambient pressure to 1125 cm at 3 GPa. Our results indicate that compression < 1.

Magnetic anisotropies of Ho(III) and Dy(III) single-molecule magnets experimentally determined polarized neutron diffraction.

We present the magnetic anisotropy of two isostructural pentagonal-bipyramidal complexes, [Ln(HO)(HMPA)]I·2HMPA (HMPA = hexamethylphosphoramide, Ln = Dy, Ho). Using ac magnetic susceptibility measurements, we find magnetic relaxation barriers of 600 K and 270 K for the Dy- and Ho-compounds, respectively. This difference is supported by polarized neutron diffraction (PND) measured at 5 K and 1 T which provides the first experimental evidence that the transverse elements in the magnetic anisotropy of the Ho-analogue are significant, whereas the Dy-analogue has a near-axial magnetic anisotropy with vanishing transverse contributions.

High-Pressure Crystallography as a Guide in the Design of Single-Molecule Magnets.

Single-molecule magnet materials owe their function to the presence of significant magnetic anisotropy, which arises from the interplay between the ligand field and spin-orbit coupling, and this is responsible for setting up an energy barrier for magnetic relaxation. Therefore, chemical control of magnetic anisotropy is a central challenge in the quest to synthesize new molecular nanomagnets with improved properties. There have been several reports of design principles targeting such control; however, these principles rely on idealized geometries, which are rarely obtained in crystal structures.