Magnetic ordering of antiferromagnets on a spatially anisotropic triangular lattice

R. F. Bishop, P. H.Y. Li, D. J.J. Farnell, Charles E Campbell

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

We study the spin-1/2 and spin-1 J1-J2 Heisenberg antiferromagnets (HAFs) on an in–nite, anisotropic, two-dimensional triangular lattice, using the coupled cluster method. With respect to an underlying square–lattice geometry the model contains antiferromag- netic (J1 > 0) bonds between nearest neighbours and competing (J02 > 0) bonds between next-nearest-neighbours across only one of the diagonals of each square plaquette, the same diagonal in each square. In a topologically equivalent triangular-lattice geometry the model has two sorts of nearest-neighbour bonds, with bonds along parallel chains and with J1 bonds providing an interchain coupling. The model thus interpolates between an isotropic HAF on the square lattice at one extreme and a set of de- coupled chains at the other, with the isotropic HAF on the triangular lattice in between at k = 1. For the spin-1/2 J1-J2 2 model, we a weakly order (or possibly second-order) quantum phase transition from a eel-ordered state to a helical state at critical point at and a second critical point at where a transition occurs between the helical state and a collinear stripe- ordered state. For the corresponding spin-1 model we an analogous transition of the second-order type at between states with and helical ordering, but we no evidence of a further transition in thiSocase to a stripe-ordered phase.

Original languageEnglish (US)
Title of host publicationCondensed Matter Theories
PublisherWorld Scientific Publishing Co.
Pages127-142
Number of pages16
ISBN (Electronic)9789814340793
ISBN (Print)9814340782, 9789814340786
DOIs
StatePublished - Jan 1 2011

Keywords

  • Coupled cluster method
  • Quantum magnet
  • Quantum phase transition

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