Emergence of a correlated electronic state via intercalation in NbSe₂

Current research in materials science focuses on creating novel functional devices through the stacking of van der Waals materials. Beyond twisted bilayer graphene, transition-metal dichalcogenides are becoming key building blocks. NbSe₂, in particular, is a notable system that exhibits both superconductivity and charge-density-wave order. It exists in several polymorphs, including 2H, 3R, 4H, and 1T. The 2H phase is metallic and superconducting, whereas the 1T phase, characterized by octahedral coordination, is reported as a Mott insulator that hosts a quantum spin-liquid ground state [1,2]. However, bulk 1T-NbSe₂ has not been successfully synthesized; it has only been observed as monolayer islands on graphene or near defects in thermally treated crystals. This absence of bulk crystals poses a significant challenge for studying its exotic correlated states. Here, we report a potential correlated state in bulk NbSe₂ stabilized through intercalation. We observe semiconducting behavior in the resistivity, reminiscent of the quantum spin liquid state in 1T-TaS₂ [3], suggesting the emergence of a correlated state. We will discuss how intercalation induces changes in the crystallographic symmetry and its connection to correlated states.



[1] L. Mengke et al., Sci. Adv. 7, eabi6339(2021).

[2] Q. Zhang et al., Nat. Commun. 15, 2336 (2024).

[3] H. Murayama et al., Phys. Rev. Research 2, 013099 (2020).