Multiple Electronic Transitions and Superconductivity in Pdₓ TiSe₂

We report the synthesis and characterization of Pdx TiSe2 via magnetization, resistivity, specific heat measurements, and low-temperature electron diffraction. At very low levels of intercalation, near Pd0.01 TiSe2, the commensurate charge density wave transition in the TiSe2 parent compound near 220 K becomes substantially stronger; a distinct transition to a more resistive state is seen at about 80 K. Originally semimetallic, TiSe2 becomes an insulator at low temperatures for 0.01≤x≤0.06 in Pdx TiSe2. Increasing Pd intercalation beyond this level begins to suppress the insulating behavior until a 2 K superconductor is found in the narrow composition range of 0.11≤x≤0.12. Beyond x=0.12, a normal metallic state (down to 0.3 K) is induced