Electronic structure and spin-orbit coupling in ternary transition metal chalcogenides Cu2TlX 2 (X=Se, Te)

Abstract

Abstract Ternary transition metal chalcogenides provide a rich platform to search and study intriguing electronic properties. Using Angle-Resolved Photoemission Spectroscopy and ab initio calculation, we investigate the electronic structure of Cu2TlX 2 (X = Se, Te), ternary transition metal chalcogenides with quasi-two-dimensional crystal structure. The band dispersions near the Fermi level are mainly contributed by the Te/Se p orbitals. According to our ab-initio calculation, the electronic structure changes from a semiconductor with indirect band gap in Cu2TlSe2 to a semimetal in Cu2TlTe2, suggesting a band-gap tunability with the composition of Se and Te. By comparing ARPES experimental data with the calculated results, we identify strong modulation of the band structure by spin-orbit coupling in the compounds. Our results provide a ternary platform to study and engineer the electronic properties of transition metal chalcogenides related to large spin-orbit coupling.