Unconventional superconductivity in nearly flat bands in twisted bilayer graphene Article Swipe
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· 2019
· Open Access
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· DOI: https://doi.org/10.1103/physrevb.99.121407
· OA: W2795196153
Flat electronic bands can accommodate a plethora of interaction driven\nquantum phases, since kinetic energy is quenched therein and electronic\ninteractions therefore prevail. Twisted bilayer graphene, near so-called the\n"magic angles", features \\emph{slow} Dirac fermions close to the\ncharge-neutrality point that persist up to high-energies. Starting from a\ncontinuum model of slow, but strongly interacting Dirac fermions, we show that\nwith increasing chemical doping away from the charge-neutrality point, a\ntime-reversal symmetry breaking, valley pseudo-spin-triplet, topological $p+ip$\nsuperconductor gradually sets in, when the system resides at the brink of an\nanti-ferromagnetic ordering (due to Hubbard repulsion), in qualitative\nagreement with recent experimental findings. The $p+ip$ paired state exhibits\nquantized spin and thermal Hall conductivities, polar Kerr and Faraday\nrotations. Our conclusions should also be applicable for other correlated\ntwo-dimensional Dirac materials.\n
