Plot of the pair density correlation function, a quantity that characterizes crystallization, in the quantum anomalous Hall crystal. Arrows on the boundary denote the topological edge states. Credit: Sheng et al.

Researchers at California State University Northridge, Stockholm University and Massachusetts Institute of Technology (MIT) recently predicted the emergence of a new quantum anomalous state of matter in fractionally filled moiré superlattice bands. Their paper, published in Physical Review Letters, predicts the existence of this state of matter in the twisted semiconductor bilayer 𝑡MoTe2.

"This class of states may be quite common in moiré superlattices, with telltale experimental signatures including a quantized and surprisingly large zero-field Hall conductance," said Emil J. Bergholtz, co-author of the paper and professor at Fysikum.

"What makes this even more remarkable is that strong Coulomb interactions drive this state. Without these interactions, the system would behave like a simple metal. However, the topology of the strongly interacting system is nevertheless manifested in terms of effectively non-interacting fermions in the form of a Chern insulating state."

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