Boundary-induced chiral-anomaly bulk states in resonant surface-plasmon crystals

Recent progress has demonstrated that chiral-anomaly bulk states can achieve similar properties to those of topological valley-Hall edge states by using a reverse strategy of boundary-induced chiral transport phenomena in some bulk modes. However, the experimental attainment of chiral-anomaly bulk states in an electromagnetic system is rarely reported. In this paper, we experimentally confirm a magnetic resonance designer surface-plasmon crystal (SPC) composed of metallic patterns deposited on a dielectric substrate, which can demonstrate boundary-induced chiral-anomaly bulk states by exploiting appropriate perfect electrical conductor boundary conditions in a finite-size two-dimensional Dirac semimetal waveguide. The proposed magnetic resonance SPC is radically distinct from photonic crystals based on Bragg scattering. The dispersion and frequency responses of the chiral transport bulk states can be tuned by adjusting the magnetic resonance frequency. Moreover, the proposed SPC can utilize almost all available guiding space, which greatly improves the utilization of materials. It is expected that the present results can be scaled to other frequencies by changing the proportional size of the magnetic resonance unit cell, which could open the possibility of designing more compact, space-efficient, and robust electromagnetic wave and microfunctional devices.