  Surface potential in a topological matter could unprecedentedly localize the
waves. However, this surface potential is yet to be exploited in topological
photonic systems. Here, we demonstrate that photonic surface states can be
induced and controlled by the surface potential in a dielectric double gyroid
(DG) photonic crystal. The basis translation in a unit cell enables tuning of
the surface potential, which in turn regulates the degree of wave localization.
The gradual modulation of DG photonic crystals enables the generation of a
pseudomagnetic field. Overall, this study shows the interplay between surface
potential and pseudomagnetic field regarding the surface states. The physical
consequences outlined herein not only widen the scope of surface states in 3D
photonic crystals but also highlight the importance of surface treatments in a
photonic system.
