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Updated: Oct 25, 2026

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Visualizing symmetry-broken Chern insulators and their quantum melting
Minhao He1, Yen-Chen Tsui1, Ran Peng2
1Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ, USA.
Abstract:
In the presence of a magnetic field, electronic states of moiré quantum materials develop a Hofstadter spectrum that provides a distinctive setting for studying the interplay between band topology and strong electron-electron interaction. Using scanning tunneling microscopy, we studied Hofstadter's states in bilayer graphene aligned with hexagonal boron nitride and directly visualized the formation of interaction-driven symmetry breaking Chern insulators. Our measurements revealed the formation of phases that double, triple, or quadruple the moiré unit cell at fractional filling of the Hofstadter bands as well as states with complex intra-unit cell wave functions. We visualized two distinct quantum phenomena in different Chern states, including quantum melting driven by the appearance and proliferation of topological defects and a quantum transition co-occurring with phase competition and separation.
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Chirality
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...

