Magnetic ordering of antiferromagnets on a spatially anisotropic triangular lattice

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

    Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

    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
    Title of host publicationCondensed Matter Theories
    EditorsEduardo V Ludena, Raymond F Bishop, Peter Iza
    PublisherWorld Scientific Publishing Co
    Pages127-142
    Number of pages16
    Volume25
    ISBN (Electronic)9789814340793
    ISBN (Print)9814340782, 9789814340786
    DOIs
    Publication statusPublished - 1 Jan 2011

    Keywords

    • Coupled cluster method
    • Quantum magnet
    • Quantum phase transition

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