Unveiling the landscape of Mottness and its proximity to superconductivity in 4Hb-TaS₂.

Abstract

Mott physics lies at the heart of many intriguing quantum phenomena. Recently, van der Waals materials emerge as a powerful platform to explore these correlated electronic states, yet tracking how such a Mott state develops and interacts with neighboring phases remains an experimental challenge. Here we use scanning tunnelling spectroscopy to study a filling-controlled Mott state and its interplay with superconductivity in 4Hb-TaS₂, which interleaves strongly correlated 1T-TaS₂ layers and superconducting 1H-TaS₂ layers. By resolving the electronic spectral function across different filling levels driven by interlayer charge transfer, we quantitatively capture the continuous evolution of the Mott state, characterized by the emergence of Mott-Hubbard bands and the systematic suppression of the central quasiparticle peak. Moreover, while the 1H layers exhibit a uniform, fully opened superconducting gap, the heavily correlated electrons in the 1T layers act destructively against pairing, creating nanoscale, non-superconducting paramagnetic puddles. Our findings provide a quintessential visualization of the iconic Hubbard model and establish layered heterostructures as an ideal playground for designing exotic correlated quantum phases.