SU(4) Skyrmions in the ν=±1 Quantum Hall State of Graphene

Phys Rev Lett. 2016 Jul 29;117(5):056806. doi: 10.1103/PhysRevLett.117.056806. Epub 2016 Jul 29.

Abstract

We explore different Skyrmion types in the lowest Landau level of graphene at a filling factor ν=±1. In addition to the formation of spin and valley pseudospin Skyrmions, we show that another type of spin-valley entangled Skyrmions can be stabilized in graphene due to an approximate SU(4) spin-valley symmetry that is affected by sublattice symmetry-breaking terms. These Skyrmions have a clear signature in spin-resolved density measurements on the lattice scale, and we discuss the expected patterns for the different Skyrmion types.