Modulating charge density wave states in 1T-TaS 2 by self-intercalation: A DFT study

Complicated charge density wave (CDW) phases transitions in the transition-metal dichalcogenide (TMDs) 1TTaS 2 have attracted wide research interest owing to the accompanied complex electronic structure transition which has not been fully understood. Inspired by a recent experimental work (Zhao et al. (2020), reported the successful preparation of Ta atom self-intercalated 2H-TaS 2 ), we employed first-principles methods to investigate Ta atom self-intercalated 1TTaS 2 , exploring effects of self-intercalation on electronic structure, magnetism, and stability ofthe charge density wave (CDW) phase in 1TTaS 2 . Our first-principle calculation shows that the intercalation of Ta atom into the van der Waals gap of 1T-TaS 2 induce the phase transition from 1T phase to CDW phase, and the positions of intercalated Ta atom determine the distribution of Davidstar clusters. Accompanied by the structural phase transition, the Ta intercalated 1T-TaS 2 also undergoes an electronic structure phase transition from non-magnetic metal to half-metal which is also different from conventional charge density wave's insulating state. When appropriate holes are doped to the intercalation system, the CDW David -star cluster is gradually destroyed and eventually returns to its original 1T phase. Our studies enrich the phase diagram of TaS 2 and highlight the effective manipulation of the CDW states via self-intercalation. This type of materials may have very promising applications in future electronic devices.