[en] Angle-resolved photoemission spectroscopy is performed to study the bulk and surface electronic structures of non-superconducting IrTe₂ and superconducting Pt_0.05Ir_0.95Te₂. In addition to the bulk electronic bands predicted by the local density approximation calculations, we observe two Dirac cone-like bands at the Brillouin zone center, which are non-dispersive along k_z, suggesting that the extra bands are surface state bands. As the experimental results are well consistent with the ab initio calculations of surface states, the parity analysis proves that these surface state bands are topologically trivial and thus exclude (Pt_xIr_1-x)Te₂ as a possible topological superconductor candidate. (authors)

[en] High-quality superconducting FeSe_0.5Te_0.5 films are epitaxially grown on different substrates by using the pulsed laser deposition method. By measuring the transport properties and surface morphology of films grown on single-crystal substrates of Al₂O₃ (0001), SrTiO₃ (001), and MgO (001), as well as monitoring the real-time growth process on MgO substrates with reflection high energy electron diffraction, we find the appropriate parameters for epitaxial growth of high-quality FeSe_0.5Te_0.5 thin films suitable for angle-resolved photoemission spectroscopy measurements. We further report the angle-resolved photoemission spectroscopy characterization of the superconducting films. The clearly resolved Fermi surfaces and the band structure suggest a sample quality that is as good as that of high-quality single-crystals, demonstrating that the pulsed laser deposition method can serve as a promising technique for in situ preparation and manipulation of iron-based superconducting thin films, which may bring new prosperity to angle-resolved photoemission spectroscopy research on iron-based superconductors. (authors)