2H-NbSe₂ is a prototypical layered transition-metal dichalcogenide exhibiting the coexistence of charge density wave (CDW) order and superconductivity. We report a comprehensive experimental and theoretical study of Ni-intercalated NbSe₂ at a composition Ni_0.19NbSe₂, where both collective electronic orders are fully suppressed. Magnetization measurements reveal a magnetically frustrated state with dominant antiferromagnetic interactions, an ordering temperature of 23.5 K, strong magnetic anisotropy, and a small net magnetic moment arising from disorder and competing exchange interactions. Electrical transport measurements show metallic behavior with no signatures of CDW or superconductivity down to 300 mK. Angle-resolved photoemission spectroscopy (ARPES) reveals a pronounced reconstruction of the electronic structure induced by Ni intercalation. In contrast to pristine NbSe₂, Ni_0.19NbSe2 exhibits an additional Γ-centered electron pocket with a band minimum at approximately 0.3 eV below the Fermi level, accompanied by significant redistribution of spectral weight across the Brillouin zone. This reconstruction cannot be explained by a rigid-band shift and is consistent with hybridization between Ni and Nb d states. Density-functional-theory calculations reproduce the emergence of the Γ-centered pocket and show a shift of the van Hove singularity away from the Fermi level. We identify this shift, together with magnetic disorder and frustration, as the primary mechanism responsible for the suppression of CDW and superconductivity. Our results place Ni_0.19NbSe^₂ in a magnetically frustrated, nonsuperconducting regime and demonstrate how magnetic intercalation and disorder can drive Fermi-surface reconstruction and destabilize electronic order in low-dimensional materials [1].

[1] A. S. Wadge, A. Kazakov, X. Gong, D. Jastrzebski, B. J. Kowalski, A. Lynnyk, Ł. Pluciński, A. Fakhredine, R. Diduszko, M. Aleszkiewicz, J. Korczak, D. Wutke, M. Rosmus, R. Kurleto, N. Olszowska, C. Autieri & A. Wiśniewski, “Magnetic frustration enforced electronic reconstruction in Ni-intercalated NbSe2: Suppression of electronic orders,” Phys. Rev. B 112, 235129 (2025).

Figure: side by side comparison of 3D Fermi surface of Pristine NbSe 2 and Ni0.19NbSe2 obtained by experiment