2025/11/05 by Shelke, A. R., Chuang, C. -W., Hamamoto, S. +7
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Strongly Correlated Electrons (cond-mat.str-el)
paper · doi:10.48550/arxiv.2511.03299
The layered 3d transition metal dichalcogenides (TMDs) CoTe2 and NiTe2 are topological Dirac Type-II metals. Their d-bands do not exhibit the expected correlation-induced band narrowing seen in CoO and NiO. We address this conundrum by quantifying the on-site Coulomb energy Udd via single-particle partial density of states and the two-hole correlation satellite using valence band resonant photoemission spectroscopy (PES), and obtain Udd = 3.0 eV/3.7 eV for CoTe2/NiTe2. Charge-transfer (CT) cluster model simulations of the measured core-level PES and x-ray absorption spectra of CoTe2 and CoO validate their contrasting electronic parameters:Udd and CT energy Δ are (3.0 eV, -2.0 eV) for CoTe2, and (5.0 eV, 4.0 eV) for CoO, respectively. The d-p hybridization strength Teg for CoTe2lt;CoO, and indicates that the reduced Udd in CoTe2 is not due to Teg. The increase in dn-count∼1 by CT from ligand to Co site in CoTe2 is due to a negative-Δ and reduced Udd. Yet, only because Udd>|Δ|, CoTe2 becomes a topological metal with p→p type lowest energy excitations. Similarly, we obtain a negative-Δ and reduced Udd in NiTe2 compared to NiO. The study reveals the nexus between negative-Δ and reduced Udd required for setting up the electronic structure framework for achieving topological behavior via band inversion in correlated metals.