Tuning superconductivity and charge density wave order in TaSe2 through Pt intercalation

Tantalum diselenide ($\mathrm{Ta}{\mathrm{Se}}_{2}$) has emerged as a promising platform to investigate the interplay between two intriguing quantum electronic states in materials: the charge density wave order (CDW) and superconductivity. In this work, we report the ability to tune these quantum electronic states by intercalating Pt into $2H\ensuremath{-}\mathrm{Ta}{\mathrm{Se}}_{2}$. By introducing 20% of Pt into $2H\ensuremath{-}\mathrm{Ta}{\mathrm{Se}}_{2}$, we demonstrate that the structural phase changes from the $2H$ to the $4{H}_{b}$ phase of $\mathrm{Ta}{\mathrm{Se}}_{2}$ with Pt atoms intercalated within the van der Waals spacing. According to the Fermi surface of the $4{H}_{b}$ phase, a Lifshitz transition occurred, destroying the Fermi-surface nesting found in the $2H$ phase. This can be attributed to the structural phase transformation and the influence of donated electrons from Pt, thus tuning the Van Hove singularities into the Fermi-level vicinity, suppressing the CDW state, and enhancing the superconducting temperature $({T}_{c})$ to $\ensuremath{\sim}2.7$ K. The resulting superconducting properties of the $4{H}_{b}\ensuremath{-}\mathrm{P}{\mathrm{t}}_{0.2}\mathrm{Ta}{\mathrm{Se}}_{2}$ are consistent with those of a BCS type-II superconductor, with a superconducting gap of 3.0 meV. Our results provide insights into the role of electron doping and structural phase changes in fine-tuning quantum electronic-state phenomena in materials. These findings could have significant implications in designing superconducting materials with tailored properties for practical applications.