First-principles study of layer-resolved anomalous Hall conductivity in surface and interface systems: topological insights

The anomalous Hall effect (AHE) has recently attracted attention for its distinct manifestations at both surfaces and in the bulk across various material systems, from magnetic insulators to magnetic metals and interfaces. It is essential to understand the contributions of different layers to the AHE to investigate the electronic and topological properties of complex materials. In this study, we advance computational methods for analyzing the AHE using a local Berry phase approach [1], achieving a decomposition of layer-specific contributions within Axion insulators through the use of hybrid Wannier functions. Our calculations align with key discoveries in Axion insulators, confirming a quantized surface anomalous Hall conductivity close to e²/2h, which reflects underlying topological characteristics. Additionally, we extend our analysis to compute the surface anomalous Nernst effect in doped systems, providing insights into how topological electronic states influence thermoelectric transport properties. Furthermore, we expand this analysis to metallic surface and interface systems, enabling a deeper understanding of the interplay between electronic structure and transport properties. In this presentation, we will share our findings regarding the layer-resolved AHE and anomalous Nernst effect in various materials, which will illustrate how examining individual layer contributions can reveal new insights into topology and improve our comprehension of transport phenomena in complex systems.

[1] H. Sawahata, N. Yamaguchi, S. Minami, and F. Ishii, Phys. Rev. B 107, 024404 (2023).