Dimensional tuning and coexisting electronic orders in single-crystalline 1T-CuₓTiSe₂ quantum materials

We report a detailed study of moderate-coupling superconductivity coexisting with charge-density-wave (CDW) order in single-crystalline 1T-CuₓTiSe₂ ( x = 0--0.1 ) down to 60 mK . Millikelvin specific-heat measurements on underdoped samples reveal a sharp superconducting anomaly with a vanishing residual electronic specific heat coefficient ( γ ᵣ → 0 ) in the ground state, signaling a fully gapped superconducting state clear of uncondensed normal electrons. Concurrently, distinct thermodynamic anomalies near 200 K and 25 K confirm the robust persistence of CDW order in the undoped and underdoped regimes, respectively. Upper critical-field measurements display a nearly temperature-independent anisotropy, Hc2ᵃᵇ/Hc2ᶜ 1.7 , consistent with conventional single-gap s -wave pairing. Analysis of the reduced specific-heat jump, Δ Cₑₗ/γ ₙ Tc , alongside the Werthamer-Helfand-Hohenberg (WHH) framework, establishes moderate electron-phonon coupling ( λ ₑₗ₋ₚₕ = 0.62 ) and conventional superconductivity coexisting with a partially suppressed CDW state. These findings present 1T-CuₓTiSe₂ as a clean model platform for investigating the systematic modulation of competing quantum phases via transition-metal intercalation, offering a strategic framework for the architectural design of low-dimensional functional electronics.