The superexchange theory predicts dominant antiferromagnetic kinetic interaction when the orbitals accommodating magnetic electrons are covalently bonded through diamagnetic bridging atoms or groups. Here we show that explicit consideration of magnetic and (leading) bridging orbitals, together with the electron transfer between the former, reveals a strong ferromagnetic kinetic exchange contribution. First-principles calculations show that it is comparable in strength with antiferromagnetic superexchange in a number of magnetic materials with diamagnetic metal bridges. In particular, it is responsible for a very large ferromagnetic coupling ($-10$ meV) between the iron ions in a ${\mathrm{Fe}}^{3+}\text{−}{\mathrm{Co}}^{3+}\text{−}{\mathrm{Fe}}^{3+}$ complex. Furthermore, we find that the ferromagnetic exchange interaction turns into antiferromagnetic by substituting the diamagnetic bridge with magnetic one. The phenomenology is observed in two series of materials, supporting the significance of the ferromagnetic kinetic exchange mechanism.

中文翻译：

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绝缘子中的铁磁动力学交换相互作用

超交换理论预测，当容纳磁性电子的轨道通过反磁性桥接原子或基团共价键合时，反铁磁动力学相互作用将占主导地位。在这里，我们显示出对磁性和（超前）架桥轨道的明确考虑，以及前者之间的电子转移，揭示了强大的铁磁动力学交换作用。第一性原理计算表明，在许多具有抗磁性金属桥的磁性材料中，其强度可与反铁磁性超交换相媲美。特别是，它负责非常大的铁磁耦合（$-10$ meV）之间的铁离子 ${铁}^{3+}\text{-}{\mathrm{有限公司}}^{3+}\text{-}{铁}^{3+}$复杂。此外，我们发现通过用磁性桥代替抗磁性桥，铁磁性交换相互作用变成反铁磁性。在两种材料中观察到了现象学，支持了铁磁动力学交换机制的重要性。