Breakthrough in Two-dimensional Material Research Unveiled by Science!

Moiré superlattices are periodic structures formed by tiny displacements between two or more two-dimensional lattices. In these moiré superlattices, the electronic behavior can be strongly influenced, giving rise to unconventional states such as quantum Hall insulators. However, achieving moiré superlattices at small twist angles remains a challenge for certain materials. This is crucial for understanding and harnessing the electron correlation effects, as electron correlation often manifests most prominently at small twist angles. However, due to experimental difficulties, the study of strong correlations in these systems has mainly focused on specific twist angles or large interlayer distortions, lacking systematic control and investigation.

Addressing this challenge, Professor Benjamin E. Feldman and his research team at Stanford University have published a recent research paper titled "Mapping twist-tuned multiband topology in bilayer WSe2" in the journal "Science." The scientists created a twisted structure of approximately 1.23° in bilayer tungsten diselenide and performed local electronic compressibility measurements using a scanning single-electron transistor microscope. They discovered the presence of multiple topological bands near this specific twist angle, exhibiting a series of quantum anomalous Hall insulators. By applying a local electric field, they also successfully induced a topological quantum phase transition. This study addresses the challenge of achieving and studying moiré superlattices at small twist angles, providing a powerful platform for further exploration of the interplay between strong correlations and topological properties.