Discovery of a Single-Band Mott Insulator in a van der Waals Flat-Band Compound

Understand

The Mott insulator provides an excellent foundation for exploring a wide range of strongly correlated physical phenomena, such as high-temperature superconductivity, quantum spin liquid, and colossal magnetoresistance.

• A Mott insulator with the simplest degree of freedom is an ideal and highly desirable system for studying the fundamental physics of Mottness.
• In this study, we have unambiguously identified such an anticipated Mott insulator in a van der Waals layered compound Nb3Cl8.
• In the high-temperature phase, where interlayer coupling is negligible, density functional theory calculations for the monolayer of Nb3Cl8 suggest a half-filled flat band at the Fermi level, whereas angle-resolved photoemission spectroscopy experiments observe a large gap.