Electronic structure study of Cu-doped 1T-TiSe2 by angle-resolved photoemission spectroscopy

We synthesized single crystals of TiSe2 with various Cu concentrations, and have performed an angle-resolved photoemission spectroscopy (ARPES) study in order to understand the CDW mechanism and to reveal the role of the Cu atoms in Cu-doped 1T-TiSe2. The measurements reveal that during the well-known charge density wave (CDW) transition the pristine TiSe2 sample undergoes a transition from a very small indirect gap semiconductor to a larger one. No nesting sign was observed in the Fermi surface in the CDW phase. The transition is suppressed in the Cu-doped samples, and an electron pocket appears near the L point, which may help appearance of the superconductivity of CuxTiSe2 through the BCS-Eliashberg relation.