Excitons in mesoscopically reconstructed moiré heterostructures

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Optics

Background:

• Moiré effects in 2D crystals create novel quantum materials with unique phenomena due to atomic registry modulations.
• Finite elasticity can cause superlattices to transition from moiré patterns to reconstructed lattices.

Purpose of the Study:

• To investigate nanoscale lattice reconstruction at the mesoscopic scale in laterally extended samples.
• To demonstrate the consequences of mesoscopic reconstruction on exciton properties in MoSe2-WSe2 heterostructures.

Main Methods:

• Optical studies of excitons in MoSe2-WSe2 heterostructures with parallel and antiparallel alignments.
• Analysis of mesoscopic reconstruction in van der Waals heterostructures with small twist angles.

Main Results:

• Identified domains with distinct effective dimensionality for moiré excitons.
• Established mesoscopic reconstruction as a key feature in real samples, influenced by finite size and disorder.
• Demonstrated rich optical phenomena arising from mesoscale domain formation.

Conclusions:

• Mesoscopic reconstruction unifies the understanding of moiré excitons in near-commensurate semiconductor heterostructures.
• This concept, applicable to other 2D material stacks, expands understanding of van der Waals heterostructures.
• Emergent topological defects and percolation networks in mesoscale domains offer new insights into electronic, optical, and magnetic properties.