Errulat Dylan, Harriman Katie L M, Gálico Diogo A, Salerno Elvin V, van Tol Johan, Mansikkamäki Akseli, Rouzières Mathieu, Hill Stephen, Clérac Rodolphe, Murugesu Muralee
Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada.
National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA.
Nat Commun. 2024 Apr 8;15(1):3010. doi: 10.1038/s41467-024-46196-w.
Single-ion anisotropy is vital for the observation of Single-Molecule Magnet (SMM) properties (i.e., a slow dynamics of the magnetization) in lanthanide-based systems. In the case of europium, the occurrence of this phenomenon has been inhibited by the spin and orbital quantum numbers that give way to J = 0 in the trivalent state and the half-filled population of the 4f orbitals in the divalent state. Herein, by optimizing the local crystal field of a quasi-linear bis(silylamido) Eu complex, the [Eu(N{SiMePh})] SMM is described, providing an example of a europium complex exhibiting slow relaxation of its magnetization. This behavior is dominated by a thermally activated (Orbach-like) mechanism, with an effective energy barrier of approximately 8 K, determined by bulk magnetometry and electron paramagnetic resonance. Ab initio calculations confirm second-order spin-orbit coupling effects lead to non-negligible axial magnetic anisotropy, splitting the ground state multiplet into four Kramers doublets, thereby allowing for the observation of an Orbach-like relaxation at low temperatures.
单离子各向异性对于在基于镧系元素的体系中观察单分子磁体（SMM）性质（即磁化强度的缓慢动力学）至关重要。就铕而言，这种现象的出现已受到自旋和轨道量子数的抑制，在三价态中这些量子数导致J = 0，而在二价态中4f轨道半充满。在此，通过优化准线性双（硅基氨基）铕配合物的局部晶体场，描述了[Eu(N{SiMePh})]单分子磁体，提供了一个铕配合物表现出磁化强度缓慢弛豫的例子。这种行为由热激活（类奥尔巴赫）机制主导，通过体磁测量和电子顺磁共振确定有效能垒约为8 K。从头算计算证实二阶自旋 - 轨道耦合效应导致不可忽略的轴向磁各向异性，将基态多重态分裂为四个克莱默斯二重态，从而使得在低温下能够观察到类奥尔巴赫弛豫。
