Yuriy Mokrousov

Affiliations

• Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany

Title

Berry phase effects in chiral magnets from first principles theory

Abstract

In ferromagnets, the anomalous Hall effect and orbital magnetism can be understood from the viewpoint of the powerful Berry phase theory. From purely theoretical grounds and in close correlation with available experiments, we show that many properties of more complex chiral magnetic structures, such as skyrmions, can be recast in the language of the Berry phases and efficiently accessed from the first principles electronic structure theory. We focus in particular on the physics of the topological Hall effect and the Dzyaloshinskii-Moriya interaction in various systems. We discuss the limits of the Berry phase approach and aim at proper definition of the topological Hall effect in the limit of very small spin textures. In particular, we demonstrate that complex real-space topology of spin textures at transition-metal surfaces can completely replace the spin-orbit interaction in giving rise to large anomalous Hall effect and orbital magnetization. This suggests that the latter two phenomena, which are traditionally viewed as key manifestations of spin-orbit interaction in solids, can be engineered and controlled via manipulation of subtle spin interactions which govern the formation of non-trivial spin structures at surfaces. To capture the main features of duiscussed effects as predicted from first principles theory we invoke simple hand-crafted tight-binding models.