Tunable Electron Correlation in Epitaxial 1T-TaS Spirals.

Tantalum disulfide (1T-TaS), being a Mott insulator with strong electron correlation, is highlighted for diverse collective quantum states in the 2D lattice, including charge density wave (CDW), spin liquid, and unconventional superconductivity. The Mott physics embedded in the 2D triangular CDW lattice has raised debates on stacking-dependent properties because interlayer interactions are sensitive to van der Waals (vdW) spacing. However, control of interlayer distance remains a challenge. Here, spiral lattices in the epitaxial TaS spirals are studied to probe collective properties with tunable interlayer interactions. A scalable synthesis of epitaxial TaS spirals is presented. A more than 50%-increased interlayer spacing enables prototype decoupled monolayers for enhanced electronic correlation exhibiting Mott physics at room-temperature and a simplified system to explore collective properties in vdW materials.