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Ab Initio Prediction of High-Temperature Magnetic Relaxation Rates in Single-Molecule Magnets
ChemRxiv Pub Date : 2021-01-20 Daniel Reta, Jon G. C. Kragskow, Nicholas Chilton
ChemRxiv Pub Date : 2021-01-20 Daniel Reta, Jon G. C. Kragskow, Nicholas Chilton
Organometallic molecules based on [Dy(CpR)2]+ cations have emerged as clear front-runners in the search for high-temperature single-molecule magnets. However, despite a growing family of structurally-similar molecules, these molecules show significant variations in their magnetic properties, demonstrating the importance of understanding magneto-structural relationships towards developing more efficient design strategies. Here we refine our ab initio spin dynamics methodology and show that it is capable of quantitative prediction of relative relaxation rates in the Orbach region. Applying it to all reported [Dy(CpR)2]+ cations allows us to tease out differences in their relaxation dynamics, highlighting that the main discriminant is the magnitude of the crystal field splitting. We subsequently employ the method to predict relaxation rates for a series of hypothetical organometallic sandwich compounds, revealing an upper limit to the effective barrier to magnetic relaxation of around 2200 K, which has been reached. However, we show that further improvements to single-molecule magnets can be made by moving vibrational modes off-resonance with electronic excitations.
中文翻译:
单分子磁体中高温磁弛豫速率的从头算预测
基于[Dy(CpR)2] +阳离子的有机金属分子已成为寻求高温单分子磁体的明确先驱。但是,尽管结构相似的分子家族不断增加,但这些分子的磁性能仍显示出显着变化,这说明了了解磁结构关系对开发更有效的设计策略的重要性。在这里,我们完善了从头算旋转动力学方法,并证明了它能够定量预测奥尔巴赫地区的相对弛豫速率。将其应用于所有报道的[Dy(CpR)2] +阳离子,可以使我们弄清它们的弛豫动力学差异,突出表明主要的判别因素是晶体场分裂的幅度。随后,我们采用该方法预测一系列假设的有机金属夹心化合物的弛豫速率,从而揭示了达到的磁弛豫有效屏障的上限约为2200K。但是,我们表明,可以通过在电子激励下使振动模式偏离共振来对单分子磁体进行进一步的改进。
更新日期:2021-01-20
中文翻译:
单分子磁体中高温磁弛豫速率的从头算预测
基于[Dy(CpR)2] +阳离子的有机金属分子已成为寻求高温单分子磁体的明确先驱。但是,尽管结构相似的分子家族不断增加,但这些分子的磁性能仍显示出显着变化,这说明了了解磁结构关系对开发更有效的设计策略的重要性。在这里,我们完善了从头算旋转动力学方法,并证明了它能够定量预测奥尔巴赫地区的相对弛豫速率。将其应用于所有报道的[Dy(CpR)2] +阳离子,可以使我们弄清它们的弛豫动力学差异,突出表明主要的判别因素是晶体场分裂的幅度。随后,我们采用该方法预测一系列假设的有机金属夹心化合物的弛豫速率,从而揭示了达到的磁弛豫有效屏障的上限约为2200K。但是,我们表明,可以通过在电子激励下使振动模式偏离共振来对单分子磁体进行进一步的改进。