Observation of Two Peculiar Types of Electronic Dispersive Structures in Thallium Selenide Studied by Angle-Resolved Photoemission Spectroscopy

Two peculiar types of electronic dispersive structures, irreproducible in bulk band calculations, have been observed in quasi-one-dimensional TlSe studied by angle-resolved photoemission spectroscopy. One is of the cross type centered at the Γ point and extending along the Γ–H–T direction parallel to the chains, which are formed along the crystallographic c-axis. The other is of the pyramid type with truncated pyramids regularly arranged along the Γ–N direction perpendicular to the chains. To an extent given by the obtained excitation photon energy dependence, the above electronic structures can be assigned to high-lying surface conduction bands resulting from secondary electron emission.