Correlated and Topological Electrons in Rhombohedral Graphene

Over the past few years, a surprisingly large number of strongly interacting electron phases have been experimentally discovered and reproduced in a variety of crystalline graphene systems Over the past few years, a surprisingly large number of strongly interacting electron phases have been experimentally discovered and reproduced in a variety of crystalline graphene systems with rhombohedral (ABC) stacking orders, including AB bilayer, ABC trilayer, ABCA tetralayer, ABCAB pentalayer, and even thicker systems. The long list of phases includes not only layer-antiferromagnetic states, large-Chern-number quantum anomalous Hall states, and quantum Hall ferroelectrics at charge neutrality, but also Stoner-like half and quarter metals, spin singlet and triplet superconductors, Wigner and Hall crystals, and orbital multiferroics near low-density van Hove singularities. When these systems are aligned with h-BN to form moiré superlattices, multiple fractional quantum anomalous Hall states have been clearly evidenced in transport experiments. Discovery and optimization of these novel phases show that RG is a superior platform with simple chemistry, rich physics, low disorder, and high tunability, advancing our understanding of the interplay between symmetry, topology, and interaction. This tutorial will provide a pedagogical introduction to the RG systems, their moiré heterostructures and unusual band structures, their experimental identification and device fabrication, and a variety of emergent correlated and topological phases in these systems. Multiscale modeling and transport/optical experiments of the RG systems will be discussed in depth with a focus on the discoveries and characteristics of these emergent phases.

Presenters:

• Fan Zhang, The University of Texas at Dallas

• Long Ju, Massachusetts Institute of Technology

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