Van der Waals heterostructures are constructed by layering atomically thin crystals such as graphene, with interlayer bonding provided by the van der Waals force. When neighboring crystal lattices are slightly mismatched, a moire pattern forms from the beating of two slightly mismatched lattices. Moire patterns can be used to generate artificial lattices for electrons, providing a versatile platform for engineering electronic structure. Of particular interest is the possibility of engineering flat electronic bands where correlations dominate in determining the electronic ground state. I will describe how these artificial lattices can be used to realize several exotic states of matter, including states where electrons appear to 'break up'--localizing a fractional of a charge on each lattice site--as well as states where electrons pair up to form a superconductor, all realized in atomically thin sheets of carbon.
Andrea Young / University of California Santa Barbara
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