Magnetic Anisotropy Switch: Easy Axis to Easy Plane Conversion and Vice Versa

Abstract

The rational design of the magnetic anisotropy of molecular materials constitutes a goal of primary importance in molecular magnetism. Indeed, the applications of molecular nanomagnets, such as single-molecule magnets and molecular magnetic refrigerants, depend on the full control over this property. Axially anisotropic magnetic systems are frequently classified as easy axis or easy plane, depending on whether the lowest energy is obtained by application of a magnetic field parallelly or perpendicularly to the unique axis. Here, the magnetic anisotropy of three lanthanide complexes is studied as a function of magnetic field and temperature. It is found that for two of these the type of magnetic anisotropy switches as a function of these parameters. Thus, this paper experimentally demonstrates that the magnetic anisotropy is not uniquely defined by the intrinsic electronic structure of the systems in question but can also be reversibly switched using external stimuli: temperature and magnetic field.

Covalency and magnetic anisotropy in lanthanide single molecule magnets: the DyDOTA archetype

“…An important contribution to the achievements in the field has been given by computational approaches 34,35. In order to rationalize the properties of lanthanide complexes on a computational basis, in the last ten years ab initio methods based on Complete Active Space Self Consistent Field36 (CASSCF) with the introduction of Spin–Orbit (SO) coupling through the Complete Active Space State Interaction37 (CASSI) proved to be able to reproduce experimental findings coming from different experimental techniques such as DC38 and AC magnetometry,39,40 electron paramagnetic resonance,41,42 cantilever torque magnetometry,39,43,44 and inelastic neutron scattering 45,46…”

NMR for Single Ion Magnets

“…But what happens when the ligand field around the metal center is fluxional? There are several reports of systems that undergo an easy-axis to easy-plane transition with increasing temperature, or for which the principal axes of magnetic susceptibility change dramatically in response to minor changes in the coordination environment [108][109][110][111][112][113]. Variations in the fundamental state configuration cause orientation changes of the axes of the magnetic susceptibility and its values.…”

Inelastic Neutron Scattering of Lanthanoid Complexes and Single‐Molecule Magnets

“…The Tb, Ho and Er analogues of 5b‐Ln have also been studied by cantilever torque magnetometry (CTM) and INS on TOFTOF at MLZ and FOCUS at SINQ . Through analysis of the sign of the magnetic torque, CTM at 2 K suggests easy‐axis magnetic anisotropy for the Ho analogue and easy‐plane magnetic anisotropy for the Tb and Er analogues.…”