Important Roles of Te 5p and Ir 5d Spin-Orbit Interactions on the Multi-band Electronic Structure of Triangular Lattice Superconductor Ir_(1-x)Pt_xTe_2

摘要

We report an angle-resolved photoemission spectroscopy (ARPES) study on a triangular lattice superconductor Ir_(1-x)Pt_xTe_2 in which the Ir-Ir or Te-Te bond formation, the band Jahn-Teller effect, and the spin-orbit interaction are cooperating and competing with one another. The Fermi surfaces of the substituted system are qualitatively similar to the band structure calculations for the undistorted IrTe_2 with an upward chemical potential shift due to electron doping. A combination of the ARPES and the band structure calculations indicates that the Te 5p spin-orbit interaction removes the p_x/p_y orbital degeneracy and induces p_x ± ip_y type spin-orbit coupling near the A point. The inner and outer Fermi surfaces are entangled by the Te 5p and Ir 5d spin-orbit interactions which may provide exotic superconductivity with singlet-triplet mixing.