SU(4) Skyrmions in the $\nu=\pm 1$ Quantum Hall State of Graphene
  We explore different skyrmion types in the lowest Landau level of graphene at a filling factor $\nu=\pm 1$. 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. 
Yunlong Lian, Achim Rosch, Mark O. Goerbig
cond-mat.mes-hall