2025/11/04 by Shelke, A. R., Chuang, C. -W., Hamamoto, S. +7
Materials Science · Physics and Astronomy · #2D Materials and Applications #FOS: Physical sciences #Graphene research and applications #Materials Science (cond-mat.mtrl-sci) #Strongly Correlated Electrons (cond-mat.str-el) #Topological Materials and Phenomena
paper · doi:10.48550/arxiv.2511.02245
openalex publication_date 2025/11/04 · openalex created_date 2025/11/06 · openalex updated_date 2026/07/28
Angle-resolved photoemission spectroscopy (ARPES) combined with band structure calculations have shown that the layered transition metal dichalcogenide(TMD) NiTe2 is a type-II Dirac semimetal. However, conflicting conclusions were reported regarding the role of electron correlations in NiTe2. We study core-levels and valence band electronic structure of single crystal NiTe2 using soft and hard x-ray photoemission spectroscopy(SXPES, HAXPES), X-ray absorption spectroscopy(XAS) and Ni 2p-3d Resonant-PES to quantify electronic parameters in NiTe2. The Ni 3d on-site Coulomb energy (Udd) is quantified from measurements of the Ni 3d single particle density of states(DOS) and the two-hole correlation satellite. The Ni 2p core level and L-edge XAS spectra are analyzed by charge-transfer (CT) cluster model calculations using the experimental Udd, and it shows that NiTe2 exhibits a negative CT energy Δ. A comparative analysis of NiO L-edge XAS confirms its well-known strongly correlated CT insulator character, with a larger Udd and positive Δ. The d-p hybridization strength Teg for NiTe2lt;NiO, and shows that Teg is not responsible for reducing Udd in NiTe\textsubscript2 compared to NiO. The negative-Δ and a reduced Udd leads to the increase in dn count on the Ni site in NiTe2 by nearly one electron. However, importantly, since Udd>|Δ|, a finite repulsive Udd results in pushing d-states away from Fermi level and this is required to make NiTe2 a moderately correlated Dirac semi-metal with band inversion in the p-p type lowest energy excitations.