Topological Phases and Their Electromagnetic Responses

Explore the fascinating world of topological materials and their unique electromagnetic properties in this comprehensive colloquium talk. Delve into the realm of three-dimensional topological insulators and their implementation of axion electrodynamics, gaining insights into magnetoelectricity across various materials. Examine the distinctive electromagnetic responses of topological Weyl and Dirac semimetals, uncovering how they address longstanding questions through the orbital moment of Bloch electrons. Discover a groundbreaking quantized effect in nonlinear optics, potentially observed experimentally, which manifests in chiral Weyl semimetals over a specific frequency range. Conclude by investigating the impact of interactions and disorder on nonlinear responses, highlighting the crucial differences between topological responses in metals and insulators.