Skyrmion zoo in graphene at charge neutrality in a strong magnetic field

Abstract

Quantum Hall ferromagnetic and skyrmion states are commonly encountered in two-dimensional systems in a strong magnetic field. Graphene is special yet again: ferromagnetism does not only involve the spin of the electrons but also their valley ``pseudospin.'' Since at charge neutrality valley and sublattice are identical, a spin-valley skyrmion has a distinctive spin pattern on the sublattices. The authors characterize a whole skyrmion zoo, where one can obtain, for instance, local antiferromagnetic patterns if the skyrmion is formed solely by spins on a single sublattice.