Optical Berry Curvature of Hinge State and Its Detection

TL;DR

This paper reveals that topological hinge states can have a nontrivial optical Berry curvature detectable via the circular photogalvanic effect, offering a new method to probe hinge state geometrical properties optically.

Contribution

It introduces the concept of hinge CPGE as a means to detect the optical Berry curvature of hinge states, demonstrated through calculations on MnBi2nTe3n+1.

Findings

Hinge states can exhibit nontrivial optical Berry curvature.

Hinge CPGE peaks reflect the optical Berry curvature.

Optical sum rule captures the Berry curvature between hinge and ground states.

Abstract

We demonstrate that the topological hinge state can possess a nontrivial optical Berry curvature in the nonAbelian formulation of the Berry curvature. It can be readily probed by the circular photogalvanic effect (CPGE), with the light illuminating a specific hinge, and we refer to it as the hinge CPGE. As a concrete example, we calculate the hinge CPGE in ferromagnetic MnBi2nTe3n+1, and find that the hinge CPGE peak structure well reflects the optical Berry curvature of hinge states and the optical sum rule captures the optical Berry curvature between the hinge state and the ground state. Thus, the hinge CPGE provides a promising route towards the optical detection of the hinge state geometrical structure.