Electronic structure of CuxZrSe2 with tetrahedrally-coordinated Cu atoms

An experimental study of the crystal and electronic structure and properties of the quasi-two-dimensional Cu_xZrSe₂ compound in the region of copper concentration, in which Cu atoms are tetrahedrally coordinated by the Se atoms, has been performed. A study of the magnetic, kinetic, and optical properties of Cu_xZrSe₂ revealed that the tetrahedral coordination of the Cu by Se atoms results in the formation of a covalent bond with a probable Cu 4s/Se 4p hybridization. A combination of soft X-ray spectroscopic methods (X-ray photoelectron spectroscopy, X-ray absorption spectroscopy and resonance photoelectron spectroscopy) with optical spectroscopy, which was used to investigate the electronic structure, confirmed this assumption. The Cu 4s/Se 4p hybrid band falls into the energy gap between the Zr 4d-derived conduction band and the Se 4p-derived valence band.