Wigner molecular crystals from multielectron moiré artificial atoms

Area of Science:

• Condensed Matter Physics
• Quantum Materials Science
• Nanotechnology

Background:

• Semiconductor moiré superlattices enable engineering of quantum solids with artificial atoms.
• Prior research focused on the Fermi-Hubbard model with simplified onsite repulsion (U).
• The behavior of multielectron artificial atoms in moiré systems remains less explored.

Purpose of the Study:

• To experimentally observe and characterize Wigner molecular crystals in moiré superlattices.
• To investigate the role of Coulomb interactions in forming these exotic electronic phases.
• To explore the tunability of Wigner molecular crystals.

Main Methods:

• Utilized scanning tunneling microscopy (STM) for high-resolution imaging.
• Fabricated twisted bilayer tungsten disulfide moiré superlattices.
• Controlled and varied experimental parameters like strain and moiré period.

Main Results:

• Observed the emergence of Wigner molecules within multielectron artificial atoms.
• Demonstrated that Coulomb interactions dominate the formation of Wigner molecules.
• Showcased the formation of a crystalline phase of electrons: the Wigner molecular crystal.
• Confirmed tunability of the Wigner molecular crystal via strain, moiré period, and carrier type.

Conclusions:

• Wigner molecular crystals are experimentally realized in twisted bilayer tungsten disulfide moiré superlattices.
• These crystals represent a novel quantum solid phase driven by strong electron-electron interactions.
• The observed Wigner molecular crystal is a highly tunable platform for exploring correlated electron phenomena.