Single‐Molecule Magnets DyM₂N@C₈₀ and Dy₂MN@C₈₀ (M=Sc, Lu): The Impact of Diamagnetic Metals on Dy³⁺ Magnetic Anisotropy, Dy⋅⋅⋅Dy Coupling, and Mixing of Molecular and Lattice Vibrations

Abstract

The substitution of scandium in fullerene single‐molecule magnets (SMMs) DySc2N@C80 and Dy2ScN@C80 by lutetium has been studied to explore the influence of the diamagnetic metal on the SMM performance of dysprosium nitride clusterfullerenes. The use of lutetium led to an improved SMM performance of DyLu2N@C80, which shows a higher blocking temperature of magnetization (TB=9.5 K), longer relaxation times, and broader hysteresis than DySc2N@C80 (TB=6.9 K). At the same time, Dy2LuN@C80 was found to have a similar blocking temperature of magnetization to Dy2ScN@C80 (TB=8 K), but substantially different interactions between the magnetic moments of the dysprosium ions in the Dy2MN clusters. Surprisingly, although the intramolecular dipolar interactions in Dy2LuN@C80 and Dy2ScN@C80 are of similar strength, the exchange interactions in Dy2LuN@C80 are close to zero. Analysis of the low‐frequency molecular and lattice vibrations showed strong mixing of the lattice modes and endohedral cluster librations in k‐space. This mixing simplifies the spin–lattice relaxation by conserving the momentum during the spin flip and helping to distribute the moment and energy further into the lattice.

Holmium(iii) molecular nanomagnets for optical thermometry exploring the luminescence re-absorption effect

“…It indicates the important role of a diamagnetic metal ion in the modification of Raman relaxation of attached paramagnetic Ho III centres which can be ascribed to the modulated phonon modes scheme going from Ho–Co ( 1 ) and Ho–Ir ( 3 ) to Ho–Rh ( 2 ) crystal lattices. 81,82 In this regard, the critical role can be played partially by the distinguishable energies of numerous available vibrational states (Fig. S1 † ) as well as by the water content which is slightly different for the Rh III analogue (see Experimental details).…”

Gadolinium as an accelerator for reaching thermal equilibrium and its influence on the ground state of Dy2GdN@C80 single-molecule magnets

“…It is only partly due to the higher Dy-Gd coupling in the antiferromagnetic states, which accounts to 2.5 k B K, but is also due to a smaller Dy-Dy exchange for the case of Dy 2 GdN@C 80 . Such variations in exchange coupling are difficult to predict but were even observed between Dy 2 ScN@C 80 and Dy 2 LuN@C 80 , where both scandium and lutetium are diamagnetic [16].…”

“…First magnetic studies were performed on Gd@C 82 [12], and it took 17 more years until SMM behavior in endohedral fullerenes was found with DySc 2 N@C 80 [13]. In the following many different C 80 mixed dysprosium-lanthanide nitride clusters have been synthesized and magnetically characterized [14][15][16]. As in other radical bridged lanthanide complexes [17] dysprosium ion pairs appear to form excellent SMMs [18].…”

Endohedral metallofullerene single molecule magnets

“…强烈混合将促进弛豫行为, 这主要是通过保持翻转的 磁矩并使其在晶格中重新分布实现的 [42] . 最近, 王太山研究组 [43] 设计并合成了内嵌3种不同 金属的氮化物金属富勒烯DyErScN@I h -C 80 , 并将其应 用于发光单分子磁体, 相比于单分子磁体, 结合光学和 磁学性质的发光单分子磁体有着更广泛的应用, 如磁 控发光器件和仿生磁接收 [44,45] .…”

“…双金属富勒烯给荧光单分子磁体的 设计提供了很好的模板, 可以通过同时内嵌一个单分 子磁体性质优异的金属离子和一个具有发光性能的金 属离子到碳笼中来构造荧光单分子磁体. 2019年, 王春 儒和王太山研究组 [91] 合成分离了DyEr@C 82 的两个异 [40,41] DySc 2 N@D 5h -C 80 5.9 17.7±0.4 [41] Dy 2 ScN@D 5h -C 80 5.3 8.4±0.2 [41] DySc 2 N@D 3 (6140)-C 68 3.8 7.6±0.4 [41] Dy 2 ScN@C s (51365)-C 84 3.3 - [41] DyLu 2 N@I h -C 80 9.5 24.2±0.7 [42] Dy 2 LuN@I h -C 80 8.0 4.3±0.2 [42] DyErScN@I h -C 80 9.0 12.5 [43] HoSc 2 N@C 80 -16.5±0.6 [47] HoLu 2 N@C 80 -- [48] CCFs Dy 2 TiC@I h -C 80 2.0 - [32] Dy 2 TiC@D 5h -C 80 2.0 - [32] Dy [88] TbGd@I h -C 80 (CH 2 Ph) 14.4 - [88] TbY@I h -C 80 (CH 2 Ph) 5.0 - [88] Tb 2 @C 79 N 28.0 - [89] DyEr@C 3v (8)-C 82 <3.0 - [91] a) "-"表示文献中未给出相应数值. b~m) 表示同一物质在不同温度区间测得的数据经拟合得到的有效能垒(U eff )值, 对应的温度区间分别 为: b) 1.8~5 K; c) 63~76 K; d) 1.6~10 K; e) 15~35 K; f) 40~53 K; g) 1.6~4 K; h) 5~47 K; i) 47~70 K; j) 10~18 K; k) >20 K; l) 1.8~10 K; m) >10 K 构体DyEr@C s (6)-C 82 和DyEr@C 3v (8) [91] .…”