Cubic 3D Chern photonic insulators with orientable large Chern vectors

TL;DR

This paper introduces a method to design 3D cubic photonic crystals with large, orientable Chern vectors that support topologically protected surface states, advancing 3D topological photonics with practical magnetic field requirements.

Contribution

It presents a novel strategy for creating 3D Chern insulators with arbitrarily large and orientable Chern vectors in weakly TRS broken photonic systems.

Findings

Supports multiple surface state channels with higher Chern numbers

Allows Chern vector orientation along any direction via magnetization

Operates with weak TRS breaking for practical applications

Abstract

Time Reversal Symmetry (TRS) broken topological phases provide gapless surface states protected by topology, regardless of additional internal symmetries, spin or valley degrees of freedom. Despite the numerous demonstrations of 2D topological phases, few examples of 3D topological systems with TRS breaking exist. In this article, we devise a general strategy to design 3D Chern insulating (3D CI) cubic photonic crystals in a weakly TRS broken environment with orientable and arbitrarly large Chern vectors. The designs display topologically protected chiral and unidirectional surface states with disjoint equifrequency loops. The resulting crystals present the following novel characteristics: First, by increasing the Chern number, multiple surface states channels can be supported. Second, the Chern vector can be oriented along any direction simply changing the magnetization axis, opening up larger 3D CI/3D CI interfacing possibilities as compared to 2D. Third, by lowering the TRS breaking requirements, the system is ideal for realistic photonic applications where the magnetic response is weak.