The interpretation and prediction of lanthanide single-ion magnets fromab initioelectronic structure calculation: the capability and limit

Abstract

Single-molecule magnet (SMM) is a fascinating system holding the potential of being revolutionary micro-electronic device in information technology. However current SMMs are still far away from real-life application due to...

Modulation of the magnetic dynamics of pentagonal-bipyramidal Co(ii) complexes by fine-tuning the coordination microenvironment

“…For the second term, n = 7 is expected for the Raman process in non-Kramers ions and n = 9 for Kramers ions, while n = 1–6 can occur for the optical acoustic Raman-like process. 4,5 Unfortunately, the inclusion of the above process gives an inappropriate result for 1 , 2 and 4 . Therefore, the synergistic contribution of direct and Orbach items may be more compatible to simulate the experimental data for these three complexes.…”

“…3 Among them, transition metal ion complexes represent an ideal platform for intelligent SMM design, due to the accumulated insights into their magneto-structural correlations. 4,5 Significant attention in this context has been devoted to Co( ii ), where large first order spin–orbit coupling (SOC) can lead to very large anisotropies. 6,7 For all reported mononuclear Co-based SMMs, one common feature is the low coordinated metal centers, and in these cases, the magnetic anisotropy can be improved by restraining the coordination number around the metal center.…”

Equatorially Positioned Halogen Ligand Effects on Single-Molecule Magnetism in a Mononuclear Dy(III) Octahedral Structure

“…In principle, the SMM performance is dictated by the magnetic relaxation in a general way that slower magnetic relaxation leads to better performance. ,,,− There are several pathways, through which magnetic relaxation proceeds, that work simultaneously. − The typical pathways are Orbach, Raman, as well as QTM. ,,,− , Each relaxation pathway is affected by various factors including the characteristics of both electronic state and vibrational state, as well as the coupling between them. − …”

“…Therefore, a completely theoretical description of Ln-SMMs ought to consider all the involved pathways, − and it tends to consume a huge computational resource, e.g., tens or even hundreds of ab initio calculations for one single system. Fortunately, such a huge burden could be avoided based on the possibility that one special pathway dominates in a given range of temperature. − , This possibility leads to a concise criterion for high-performance SMM, i.e., the coexistence of a long QTM time τ QTM and high effective barrier of magnetic reversal U eff . − This criterion is not necessarily sufficient, but it has been verified to be reliable if applied in systems having similar coordination geometry τ QTM − 1 = 2 h · Δ tun 2 false( ε normalbias 2 + 4 normalΔ normaltun 2 false) 1 / 2 τ QTM − 1 = β B ave h · g XY 2 2 false( normalg italicXY 2 + normalg italicZ 2 false) …”

“…According to previous experience, , an empirical B ave of 20 mT is adopted here. When the anisotropy of magnetic field is considered, a more sophisticated eq is obtained with the introduction of x aniso as a parameter characterizing the anisotropy of B⃗ (eq ).…”