Kavli Affiliate: Debanjan Chowdhury
| First 5 Authors: Xuepeng Wang, Xuepeng Wang, , ,
| Summary:
The study of interacting topological bands with a tunable bandwidth offers a
unique platform to study the interplay of intertwined orders and emergent
non-electronic excitations. Here we design a time-reversal symmetric and
sign-problem-free electronic model with tunable Chern bands carrying
valley-contrasting Chern number, interacting via competing (anti-)ferromagnetic
interactions. Using numerically exact quantum Monte-Carlo computations, we
analyze the many-body phase-diagram as a function of temperature and band
filling fractions over a wide range of electronic bandwidth, interaction
anisotropy, and an Ising spin-orbit coupling. At a commensurate filling of the
Chern bands, the ground state hosts intra-valley ferromagnetic coherence and
inter-valley antiferomagnetism, thus realizing an insulating Chern
antiferromagnet (CAF). Upon doping, the ground-state develops
superconductivity, but where the low-energy charged quasiparticles are
composite objects — electrons dressed by multiple spin-flip excitations. These
spin-polaron (or skyrmion) excitations persist in the presence of a weak
spin-orbit coupling. In a companion article, we address the emergent symmetries
and low-energy field-theoretic aspects of the problem and reveal the proximity
to a deconfined quantum critical point. We end by providing a general outlook
towards building microscopic connections with models of interacting moir’e
materials, including twisted bilayer graphene, where many of the ingredients
considered here are naturally present.
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