Correlation-driven origin of shallow electron pocket in Co${}_{1/3}$TaS${}_2$ revealed by ARPES and cluster perturbation theory

Abstract

We investigate the electronic structure and Fermi surface of Co${}_{1/3}$TaS${}_2$ using angle-resolved photoemission spectroscopy (ARPES) combined with theoretical modeling beyond standard density functional theory (DFT+U). A shallow electron pocket, the so-called $\beta$ feature, is observed at the Fermi level near the corner of the superlattice Brillouin zone, representing the first experimental observation of this feature in an intercalated TaS${}_2$ compound. Similar pockets have been reported in $X_{1/3}$NbS${}_2$ ($X$ = Co, Cr, Ni), where their surface versus bulk origin remains actively debated. Because conventional DFT+U does not capture this feature, we employ cluster perturbation theory (CPT) to incorporate an explicit treatment of strong electron correlations ($U$) on the Co sites. CPT successfully reproduces the $\beta$ feature, demonstrating its origin from correlation-driven bulk states rather than surface effects. To further substantiate this conclusion, we studied a reduced Co-content sample, Co${}_{0.22}$TaS${}_2$, where the reduced charge transfer modifies the Co-derived states near the Fermi level. Its electronic structure remains largely similar to that of pristine 2H-TaS${}_2$, showing only a minor overall energy shift and lacking the $\beta$ feature, consistent with disrupted long-range Co ordering and modified orbital character near the Fermi level. We demonstrate that the $\beta$ feature arises from strong local correlations on the Co sites and requires long-range crystallographic order among intercalated Co atoms to maintain coherence. These results highlight the importance of strong electronic correlations in magnetically intercalated transition-metal dichalcogenides and provide a microscopic understanding of features not captured by conventional DFT+U.

11 pages, 6 figures, 1 table

References in corpus (25)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Advanced capabilities for materials modelling with Quantum ESPRESSO
• Half-metallic ferromagnets: From band structure to many-body effects
• Self-consistent Hubbard parameters from density-functional perturbation theory in the ultrasoft and projector-augmented wave formulations
• Double Counting in LDA+DMFT - The Example of NiO
• Spontaneous topological Hall effect induced by non-coplanar antiferromagnetic order in intercalated van der Waals materials
• Computing total energies in complex materials using charge self-consistent DFT+DMFT
• Giant anomalous Hall effect in quasi-two-dimensional layered antiferromagnet Co${}_{1/3}$NbS${}_2$
• Tetrahedral triple-Q magnetic ordering and large spontaneous Hall conductivity in the metallic triangular antiferromagnet Co1/3TaS2
• Field-tunable toroidal moment and anomalous Hall effect in noncollinear antiferromagnetic Weyl semimetal Co1/3TaS2
• The nature of ferromagnetism in the chiral helimagnet $C{r}_{1/3}Nb{S}_2$
• Large anomalous Hall effect induced by weak ferromagnetism in the noncentrosymmetric antiferromagnet $\mathrm{Co}{\mathrm{Nb}}_3{\mathrm{S}}_6$
• Consistent LDA'+DMFT -- an unambiguous way to avoid double counting problem: NiO test
• Composition dependence of bulk properties in the Co-intercalated transition-metal dichalcogenide Co${}_{1/3}$TaS${}_2$
• Role of intercalated Cobalt in the electronic structure of Co${}_{1/3}$NbS${}_2$
• Visualizing the out-of-plane electronic dispersions in an intercalated transition metal dichalcogenide
• Narrowing of d bands of FeCo layers intercalated under graphene
• Electrical and thermal transport in van der Waals magnets 2H-M${}_x$TaS${}_2$ (M = Mn, Co)
• Magnetic interactions in intercalated transition metal dichalcogenides: a study based on ab initio model construction
• Gapped nodal planes drive a large topological Nernst effect in a chiral lattice antiferromagnet
• Electrical control of topological 3Q state in intercalated van der Waals antiferromagnet Cox-TaS2
• Darkness in interlayer and charge density wave states of 2H-TaS2
• Topological Magneto-optical Kerr Effect without Spin-orbit Coupling in Spin-compensated Antiferromagnet
• Experimental confirmation of the magnetic ordering transition induced by an electronic structure change in the metallic triangular antiferromagnet Co${}_{1/3}$TaS${}_2$
• Spin-Valley Locking in 2H-TaS2 and Its Co-Intercalated Counterpart: Roles of Surface Domains and Co Intercalation