Anatomy of the modern theory of orbital magnetism from first-principles: term-by-term analysis in the gauge-covariant formalism
现代轨道磁性理论的解剖:基于第一性原理的项级分析:在规范协变形式中的分析
Hojun Lee, Insu Baek, Mirco Sastges, Yuriy Mokrousov, Hyun-Woo Lee, Dongwook Go
AI总结 本文基于现代理论,通过Berry相分析不同材料中的轨道磁性,探讨了带结构特征的微观性质,并揭示了轨道磁性与化学性质的相互作用。
Comments 36 pages, 12 figures, Accepted version in Phys. Rev. B
详情
- Journal ref
- Physical Review B (2026)
我们通过所谓的现代理论,基于Berry相,深入分析了轨道磁性,涵盖了过渡金属、sp金属和过渡金属二硫化物等不同材料类别,突出带结构特征的微观性质。我们采用Lopez等人提出的规范协变形式的现代理论,使在任一选择的Wannier函数规范下都能控制计算轨道磁性,并给出总贡献作为规范不变的可测量。这能一致地捕捉到Wannier基函数的异常位置、速度和轨道角动量的贡献,以及哈密顿量的贡献,其总和是规范不变的。对于过渡金属,我们发现原子中心近似捕捉了现代理论给出的大部分总贡献,这归因于d电子的局域性质。然而,5d金属相比3d金属表现出更大的两种方法之间的偏差,因为5d电子比3d电子更非局域化。另一方面,sp金属表现出两种方法之间的强烈偏差,其中sp电子的动能很重要。最后,在1H-MoS2中,我们发现由于价带和导带之间在直接带隙中的相干混合,谷轨道动量远超d电子的原子极限。我们的工作阐明了电子轨道的化学性质和带结构效应的一致相互作用,并突显了Berry相在轨道磁性中的作用。结果表明,轨道电子学在控制原子轨道之外有广阔前景,通过利用Berry相可显著增强轨道磁性。
We present an in-depth analysis of the orbital magnetism by means of the so-called modern theory based on the Berry phase across distinct classes of materials-d transition metals, sp metals, and transition metal dichalcogenides-highlighting the microscopic nature of band structure characteristics. We adopt a gauge-covariant formulation of the modern theory proposed in [Lopez et al. Phys. Rev. B 85, 014435 (2012)], which enables the calculation of orbital magnetism in a controlled manner in any chosen gauge of Wannier functions and gives the total contribution as a gauge-invariant measurable. This captures consistently the contributions due to the anomalous position, velocity, and orbital angular momentum of Wannier basis, as well as the contributions due to Hamiltonian such that their sum is gauge-invariant. For d transition metals, we find that the atom-centered approximation captures the majority of the total contribution given by modern theory, which we attribute to localized nature of d electrons. However, 5d metals tend to exhibit larger deviation between the two methods than 3d metals do, as 5d electrons are more delocalized than 3d electrons. On the other hand, sp metals exhibit a strong deviation between the two methods, where large kinetic energy of sp electrons is important. Finally, in 1H-MoS2, we find that the valley orbital moment far exceeds the atomic limit of d electrons due to coherent hybridization between valence and conduction bands in direct band gaps. Our work elucidates the interplay of the chemical nature of electronic orbitals and the effect of band structures in a consistent manner and highlights the role of Berry phase in orbital magnetism. The results suggest a promising direction of orbitronics beyond controlling atomic orbitals, in which the orbital magnetism can be greatly enhanced by exploiting Berry phase.