Regensburg 2025 – scientific programme

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O: Fachverband Oberflächenphysik

O 86: Electronic Structure of Surfaces: Spectroscopy, Surface States II

O 86.4: Talk

Thursday, March 20, 2025, 15:45–16:00, H2

Electronic structure of the correlated topological metals CoTe₂ and NiTe₂ — Abhijeet Shelke¹, Chien-Wen Chuang², Truc Ly Nguyen¹, Yo-Xun Chen¹, Masato Yoshimura¹, Nozomu Hiraoka¹, Satoru Hamamoto³, Masaki Oura³, Chia-Nung Kuo⁴, Chin-Shan Lue⁴, Atsushi Fujimori^5,1, and •Ashish Chainani¹ — ¹National Synchrotron Radiation Research Center, Hsinchu 300092, Taiwan — ²Dept. of Physics, Tohoku University, Sendai 980-8578, Japan — ³RIKEN SPring-8 Center, Hyogo 679-5148, Japan — ⁴Dept. of Physics, NCKU, Tainan 70101, Taiwan — ⁵Dept. of Physics, The University of Tokyo, Tokyo 113-0033, Japan

The transition-metal(TM) tellurides CoTe₂ and NiTe₂ are known to exhibit topological semi-metallic Dirac bands from ARPES studies. We carry out core level and valence band measurements using hard x-ray photoemission spectroscopy(HAXPES), x-ray absorption spectroscopy(XAS) and TM 2p−3d resonant photoemission spectroscopy(R-PES) to study electronic structure of CoTe₂ and NiTe₂. The R-PES spectra show clear evidence of TM LVV Auger two-hole correlation satellites. Using the Cini-Sawatzky method, we estimate an on-site Coulomb energy, U_dd∼3 eV for Co in CoTe₂, and U_dd∼4 eV for Ni in NiTe₂. Using these values in charge-transfer cluster model calculations, we simulate the TM 2p HAXPES core level and L-edge XAS spectra of CoTe₂ and NiTe₂. The electronic parameter analyses indicate a negative charge transfer energy Δ for both CoTe₂ and NiTe₂. The results indicate a p-type metal in terms of the Zaanen-Sawatzky-Allen phase diagram for CoTe₂ and NiTe₂.

Keywords: Electronic structure; correlated electrons; topological metals; hard x-ray photoemission spectroscopy; resonant photoemission spectroscopy