This study reports the fabrication of artificial molecules composed of lead (Pb) atoms on a van der Waals crystal, specifically the honeycomb charge-order superstructure of IrTe2. Pb atoms form clusters ranging from dimers to heptamers, including benzene-shaped hexamers. Tunneling spectroscopy and electronic structure calculations reveal the formation of unusual relativistic molecular orbitals within these clusters. Spin-orbit coupling is crucial for the formation of Dirac electronic states and stabilizes the artificial molecules by reducing adatom-substrate interaction. Lead atoms are shown to be particularly suitable for maximizing the relativistic effect. This work demonstrates a novel approach to fabricating artificial molecules with unique properties using two-dimensional orderings as templates.

Jae Whan Park, Hyo Sung Kim, Thomas Brumme, Thomas Heine, Han Woong Yeom