title: Power-law spin correlations in a perturbed spin model on a honeycomb lattice.
abstract: We consider the spin-1/2 model on the honeycomb lattice in the presence of a weak magnetic field hα << 1. Such a perturbation destroys the exact integrability of the model in terms of gapless fermions and static Z2 fluxes. We show that it results in the appearance of a long-range tail in the irreducible dynamic spin correlation function: <<s(z)(t,r)s(z)(0,0)>> ∝ h(z)(2)f(t,r), where f(t,r) ∝ [max(t,r)]-4 is proportional to the density polarization function of fermions.
authors.affiliation: LD Landau Institute for Theoretical Physics, Kosygin street 2, Moscow 119334, Russia.
authors.forename: K S
authors.initials: KS
authors.lastname: Tikhonov
authors.forename: M V
authors.initials: MV
authors.lastname: Feigel'man
authors.forename: A Yu
authors.initials: AY
authors.lastname: Kitaev