Superconductivity related to the suppression of exciton formation in 1T-TiSe2

In strongly correlated electron system, the impact of elementary substitution or intercalation plays a crucial role in determining electronic ground state among various macroscopic quantum phases such as charge order and superconductivity. Here, we report that simultaneous Cu intercalation and Ta substitution at Ti site in 1T-Cu x Ti0.8Ta0.2Se2 induce an intrinsic electronic phase diagram, characterized by an inherent superconducting transition in the x region of 0 ⩽ x ⩽ 0.12, with a maximum superconducting transition temperature T c of 2.5 K for x = 0.04, in contrast to the non-superconducting sample 1T-Cu0.04TiSe2. The increased density of free charge carriers screen the Coulomb interaction between electron-hole pairs effectively, promoting the occurrence of superconductivity favourably. Present results suggest that the Cu intercalation and the Ta substitution-induced suppression of the exciton condensation boost the superconductivity, shedding new light on the fundamental physics of the interplay between superconductivity, charge order, and electron correlation.