Charge order with unusual star-of-David lattice in monolayer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi>NbTe</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:math>
Taiki Taguchi, K. Sugawara, Hirofumi Oka, Tappei Kawakami, Yasuaki Saruta, Takemi Kato, K. Nakayama, S. Souma, T. Takahashi, Tomoteru Fukumura, T. Sato
Abstract
The authors fabricated a new two-dimensional material, monolayer NbTe${}_{2}$, and investigated its electronic states. They discovered a charge-density wave with a \ensuremath{\surd}19\ifmmode\times\else\texttimes\fi{}\ensuremath{\surd}19 periodicity, accompanied by partially occupied metallic star-of-David clusters of Nb atoms, which is in sharp contrast to the fully occupied Mott-insulating monolayer NbSe${}_{2}$. Such an intriguing difference is found to originate from the underlying fermiology and hidden-Fermi-surface nesting. The present result lays the foundation for manipulating the two-dimensional Mott-insulator phase.