Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, Lab of Theoretical Molecular Magnetism (LTMM), College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, P. R. China.
Phys Chem Chem Phys. 2023 Jul 12;25(27):18387-18399. doi: 10.1039/d3cp01766d.
Single-molecule magnets (SMMs) have great potential in becoming revolutionary materials for micro-electronic devices. As one type of SMM and holding the performance record, lanthanide single-ion magnets (Ln-SIMs) stand at the forefront of the family. Lowering the coordination number (CN) is an important strategy to improve the performance of Ln-SIMs. Here, we report a theoretical study on a typical group of low-CN Ln-SIMs, , tetracoordinated structures. Our results are consistent with those of experiments and they identify the same three best Ln-SIMs a concise criterion, , the co-existence of long and high . Compared to the record-holding dysprosocenium systems, the best SIMs here possess values that are shorter by several orders of magnitude and values that are lower by ∼1000 Kelvin (K). These are important reasons for the fact that the tetracoordinated Ln-SIMs are clearly inferior to dysprosocenium. A simple but intuitive crystal-field analysis leads to several routes to improve the performance of a given Ln-SIM, including compression of the axial bond length, widening the axial bond angle, elongation of the equatorial bond length and usage of weaker equatorial donor ligands. Although these routes are not brand-new, the most efficient option and the degree of improvement resulting from it are not known in advance. Consequently, a theoretical magneto-structural study, covering various routes, is carried out for the best Ln-SIM here and the most efficient route is shown to be widening the axial ∠O-Dy-O angle. The most optimistic case, having a ∠O-Dy-O of 180°, could have a (up to 10 s) and (∼2400 K) close to those of the record-holders. Subsequently, a blocking temperature () of 64 K is predicted to be possible for it. A more practical case, with ∠O-Dy-O being 160°, could have a of up to 400 s, of around 2200 K and the possibility of a of 57 K. Although having an inherent precision limit, these predictions provide a guide to performance improvement, starting from an existing system.
单分子磁体 (SMM) 在成为微电子设备的革命性材料方面具有巨大潜力。作为 SMM 的一种类型，镧系单离子磁体 (Ln-SIM) 处于该家族的前沿。降低配位数 (CN) 是提高 Ln-SIM 性能的重要策略。在这里，我们报告了对一组典型的低 CN Ln-SIM 的理论研究，即四配位结构。我们的结果与实验结果一致，并确定了相同的三个最佳 Ln-SIM，即简洁的标准，长和高的同时存在。与保持记录的镝系系统相比，这里最好的 SIMs 具有短几个数量级的 值和低约 1000 开尔文 (K) 的 值。这就是为什么四配位 Ln-SIM 明显不如镝系的重要原因。简单而直观的晶体场分析导致了几种提高给定 Ln-SIM 性能的途径，包括轴向键长的压缩、轴向键角的加宽、赤道键长的延长和使用较弱的赤道供体配体。尽管这些途径并不新鲜，但事先不知道哪种途径最有效，以及由此带来的改进程度。因此，对这里最好的 Ln-SIM 进行了各种途径的理论磁结构研究，结果表明最有效的途径是加宽轴向∠O-Dy-O 角。最乐观的情况是∠O-Dy-O 为 180°，则可能具有高达 10 s 的 值和接近记录保持者的约 2400 K 的 值。随后，预测其 可达到 64 K。对于具有∠O-Dy-O 为 160°的更实际的情况，可能具有高达 400 s 的 值、约 2200 K 的 值和 57 K 的 的可能性。尽管具有固有精度限制，但这些预测为从现有系统开始提高性能提供了指导。
