Intrinsic hyperbolicity in two-dimensional Dirac Su-Schrieffer-Heeger materials

Hyperbolic surface plasmon polaritons (SPPs) enable highly directional energy transport and enhanced photonic density of states, but current implementations often rely on artificially engineered metamaterials, which restrict bandwidth, tunability and loss performance. This study establishes a minimal two-dimensional (2D) Dirac Su-Schrieffer-Heeger (SSH) framework, where glide mirror symmetry decouples intraband and interband channels, giving rise to natural hyperbolic windows. First-principles calculations reveal that a zigzag-buckled (ZB) ${\mathrm{C}}_{4}\mathrm{N}$ monolayer is a promising candidate for achieving low-loss hyperbolicity across broad spectral ranges predicted by the SSH model. Additionally, applying uniaxial strain allows for continuous tuning of hyperbolic intervals and surface plasmon propagation. These findings pave the way for pattern-free, reconfigurable plasmonic devices, and broaden the design principles for exploiting nonsymmorphic symmetries in 2D quantum materials.