In the 1980s, the discovery of electron states that fractionalize in the presence of a time-reversal symmetry breaking magnetic field opened up new directions in condensed matter physics. In 2023, evidence has accumulated that a version of these states in which the time-reversal symmetry breaking is spontaneous appears in moiré materials.
Key advances
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Experimentalists have developed and refined techniques for flexible stacking of atomic scale 2D materials isolated from van der Waals layer compounds.
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Theorists have improved understanding of how ideal quantum geometry can lead to electronic correlations in the Bloch bands of a two-dimensional crystal that are similar to those favoured by strong magnetic fields.
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Twisted bilayer MoTe2 and graphene multilayer moiré materials, identified theoretically as attractive targets, have now been definitively established as fractional quantum anomalous Hall state hosts.
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Morales-Durán, N., Shi, J. & MacDonald, A.H. Fractionalized electrons in moiré materials. Nat Rev Phys (2024). https://doi.org/10.1038/s42254-024-00718-z
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DOI: https://doi.org/10.1038/s42254-024-00718-z
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