Robust Topological Surface States and Enhanced Superconductivity in Self-Intercalated PdTe2.

Intercalation within van der Waals gaps of layered materials is a powerful approach for tuning their physical properties. However, the role of self-intercalation remains largely unexplored, particularly with respect to topological states and superconductivity. Using first-principles calculations, we systematically studied the Dirac semimetal PdTe2 and its self-intercalated derivative, PdTe. We found that PdTe2 hosts a type-II bulk Dirac point, while PdTe possesses a type-I bulk Dirac point. This demonstrates that self-intercalation can fundamentally alter the character and energy position of bulk Dirac Fermions. In both compounds, pronounced topological surface states persist near Fermi level, indicating their robustness against structural modification. Notably, PdTe exhibits a superconducting transition temperature more than twice that of PdTe2, arising from an increased density of states at the Fermi level and enhanced electron-phonon coupling. These results establish self-intercalation as an effective strategy for engineering the topological electronic structure and superconductivity of layered transition-metal chalcogenides.