Zero-energy states and fragmentation of spin in the easy-plane antiferromagnet on a honeycomb lattice

Abstract

The core of the vortex in the Neel order parameter for an easy-plane antiferromagnet on honeycomb lattice is demonstrated to bind two zero-energy states. Remarkably, a single electron occupying this mid-gap band has its spin fragmented between the two sublattices: Whereas it yields a vanishing total magnetization it shows a finite Neel order, orthogonal to the one of the assumed background. The requisite easy-plane anisotropy may be introduced by a magnetic field parallel to the graphene layer, for example. The results are relevant for spin-1/2 fermions on graphene's or optical honeycomb lattice, in the strongly interacting regime.

arXiv comment4 pages; cosmetic changes; published version

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• Interactions and phase transitions on graphene's honeycomb lattice
• Electron fractionalization in two-dimensional graphenelike structures
• Ghost excitonic insulator transition in layered graphite
• QED3 theory of underdoped high temperature superconductors
• Ground state and finite temperature signatures of quantum phase transitions in the half-filled Hubbard model on a honeycomb lattice
• Theory of integer quantum Hall effect in graphene
• Antiferromagnetism from phase disordering of a d-wave superconductor
• SO(3) symmetry between Neel and ferromagnetic order parameters for graphene in a magnetic field
• Universality and the magnetic catalysis of chiral symmetry breaking
• Topological degeneracy of non-Abelian states for dummies
• Effective theory of high-temperature superconductors

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