  The layered transition metal chalcogenides have been a fertile land in solid
state physics for many decades. Various MX2-type transition metal
dichalcogenides, such as WTe2, IrTe2, and MoS2, have triggered great attention
recently, either for the discovery of novel phenomena or some extreme or exotic
physical properties, or for their potential applications. PdTe2 is a
superconductor in the class of transition metal dichalcogenides, and
superconductivity is enhanced in its Cu-intercalated form, Cu0.05PdTe2. It is
important to study the electronic structures of PdTe2 and its intercalated form
in order to explore for new phenomena and physical properties and understand
the related superconductivity enhancement mechanism. Here we report systematic
high resolution angle-resolved photoemission (ARPES) studies on PdTe2 and
Cu0.05$PdTe2 single crystals, combined with the band structure calculations. We
present for the first time in detail the complex multi-band Fermi surface
topology and densely-arranged band structure of these compounds. By carefully
examining the electronic structures of the two systems, we find that
Cu-intercalation in PdTe2 results in electron-doping, which causes the band
structure to shift downwards by nearly 16 meV in Cu0.05PdTe2. Our results lay a
foundation for further exploration and investigation on PdTe2 and related
superconductors.
