Inelastic Neutron Scattering of Lanthanoid Complexes and Single‐Molecule Magnets

Abstract

Single‐molecule magnets (SMMs) are discrete metal complexes that retain their magnetisation below a certain temperature, with possible applications in quantum information processing, molecular spintronics and high‐density data storage. Complexes of lanthanoid(III) ions have proven highly successful in the field, some exhibiting magnetic hysteresis at liquid nitrogen temperatures. Inelastic neutron scattering (INS), widely used for the study of the crystal field splitting engendered by the coordination environment of metal centres, can afford a wealth of information when applied to the study of these molecular nanomagnets, as the SMM properties arise from the electronic structure of the lanthanoid(III) ions. Although relatively underutilised to date, INS can be employed alongside crystal field analysis, and/or ab initio calculations, to understand how subtle structural changes impact SMM behaviour. In this Minireview we discuss the application of INS to the study of lanthanoid complexes, to elucidate both crystal field splitting and exchange coupling in coupled metal‐radical and metal‐metal SMMs.

Correlating axial and equatorial ligand field effects to the single-molecule magnet performances of a family of dysprosium bis-methanediide complexes

“… 3 Ln-based SMMs have been amenable to systematic improvement by optimisation of the crystal field (CF) generated by the coordination environment in order to best stabilise the most magnetic projections of the spin–orbit coupled total angular momentum ( m J states). 4 This approach has permitted design of large barriers to magnetisation reversal, U eff , over which magnetic relaxation occurs with an Arrhenius-like exponential temperature dependence, and thus larger U eff values should lead to slower magnetic relaxation at a given temperature. This is well established for Dy III , where near-linear coordination environments stabilise the m J = |±15/2〉 ground state.…”

Inter-Kramers Transitions and Spin–Phonon Couplings in a Lanthanide-Based Single-Molecule Magnet

“…Another experimental technique is inelastic neutron scattering (INS), which has also occasionally been used to probe magnetic excitations in molecular f-element compounds. ,− The following methods have been used to distinguish magnetic excitations in INS: , (1) Unique, different dependences of the magnetic peak and phonon peak intensities on the scattering angles in INS; (2) temperature dependence; , and (3) diamagnetic controls. , It should be noted that it may be challenging to find magnetic peaks in samples with large numbers of H atoms by INS spectra from a direct-geometry spectrometer . This is due to the large incoherent scattering cross-section of the H atoms, contributing to strong vibrational intensities that overshadow the magnetic excitation in the INS spectra .…”

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…”