Bouammali Mohammed-Amine, Suaud Nicolas, Martins Cyril, Maurice Rémi, Guihéry Nathalie
Laboratoire de Chimie et Physique Quantiques, UMR5626, Université de Toulouse 3, Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France.
SUBATECH, UMR CNRS 6457, IN2P3/IMT Atlantique/Université de Nantes, 4 rue A. Kastler, 44307 Nantes Cedex 3, France.
J Chem Phys. 2021 Apr 7;154(13):134301. doi: 10.1063/5.0045569.
This paper is a theoretical "proof of concept" on how the on-site first-order spin-orbit coupling (SOC) can generate giant Dzyaloshinskii-Moriya interactions in binuclear transition metal complexes. This effective interaction plays a key role in strongly correlated materials, skyrmions, multiferroics, and molecular magnets of promising use in quantum information science and computing. Despite this, its determination from both theory and experiment is still in its infancy and existing systems usually exhibit very tiny magnitudes. We derive analytical formulas that perfectly reproduce both the nature and the magnitude of the Dzyaloshinskii-Moriya interaction calculated using state-of-the-art ab initio calculations performed on model bicopper(II) complexes. We also study which geometrical structures/ligand-field forces would enable one to control the magnitude and the orientation of the Dzyaloshinskii-Moriya vector in order to guide future synthesis of molecules or materials. This article provides an understanding of its microscopic origin and proposes recipes to increase its magnitude. We show that (i) the on-site mixings of 3d orbitals rule the orientation and magnitude of this interaction, (ii) increased values can be obtained by choosing more covalent complexes, and (iii) huge values (∼1000 cm) and controlled orientations could be reached by approaching structures exhibiting on-site first-order SOC, i.e., displaying an "unquenched orbital momentum."
本文是一篇关于现场一阶自旋轨道耦合（SOC）如何在双核过渡金属配合物中产生巨大的Dzyaloshinskii-Moriya相互作用的理论“概念验证”。这种有效相互作用在强关联材料、斯格明子、多铁性材料以及在量子信息科学与计算中有潜在应用的分子磁体中起着关键作用。尽管如此，从理论和实验上确定它仍处于起步阶段，并且现有体系通常表现出非常小的量级。我们推导了分析公式，这些公式能够完美重现使用对模型双铜（II）配合物进行的最先进的从头算计算所得到的Dzyaloshinskii-Moriya相互作用的性质和量级。我们还研究了哪些几何结构/配体场力能够控制Dzyaloshinskii-Moriya矢量的量级和方向，以便为未来分子或材料的合成提供指导。本文阐述了其微观起源，并提出了增大其量级的方法。我们表明：（i）3d轨道的现场混合决定了这种相互作用的方向和量级；（ii）通过选择更多的共价配合物可以得到更大的值；（iii）通过接近表现出现场一阶SOC的结构，即显示出“未猝灭的轨道动量”的结构，可以达到巨大的值（约1000 cm）并实现可控的方向。
