Přednášející
Popis
Berry curvature expresses the curvature of the reciprocal space, in a similar manner as magnetic field express curvature of the real space, resulting in a curved transport of electrons in solids. Therefore, Berry curvature is a key to describe various transport phenomena such as anomalous Hall effect, anomalous Nerst effect, orbital magnetization, topological insulators or electric polarization. As those transports are lossless (also called bound current or topological current), they are interesting for various applications.
It is well known that Berry curvatures arise from close proximity of hybridizing bands, providing topological flows of Berry curvature in form of monopoles, one- (two-) dimensional flows, and or transitions between different dimensionalities [1] (Fig. 1). We use those features to identify and to visualize topological features of electronic band structure itself, such as dimensionality of avoided band degeneracy (e.g. where and at which dimensionality the bands approach each other or get degenerated). This provides a novel unique view on details of the electronic structure in whole Brillouin zone, inaccessible with traditional understanding of the band structure. Finally, we will demonstrate relation between Berry curvature and anomalous Hall effect in bcc Fe [1] and anomalous Nerst effect in Fe3Ga [2].
[1] Stejskal et al, Sci Rep 12, 97 (2022) [doi:10.1038/s41598-021-00478-1]
[2] Stejskal et al, Phys. Rev. Materials 7, 084403 (2023) [doi:10.1103/PhysRevMaterials.7.084403]
