2008/08/16 by Marcelo Arlego, Wolfram Brenig
Physics and Astronomy · #Advanced Condensed Matter Physics #Physics of Superconductivity and Magnetism #Theoretical and Computational Physics #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.78.224415
6 pages, 5 figures
arxiv created 2008/08/16 · openalex publication_date 2008/12/17 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
Series expansion based on the flow equation method is employed to study the zero-temperature properties of the spin-1/2 J1\text\ensuremath-J2\text\ensuremath-J3 antiferromagnet in two dimensions. Starting from the exact limit of decoupled plaquettes in a particular generalized J1\text\ensuremath-J2\text\ensuremath-J3 model, we analyze the evolution of the ground-state energy and the elementary triplet excitations in powers of all three interplaquette couplings up to fifth order. We find that the plaquette phase remains stable over a wide range of exchange couplings and connects adiabatically up to the case of the plain J1\text\ensuremath-J2\text\ensuremath-J3 model but not to the J1\text\ensuremath-J2 model at J3=0. Besides confirming the existence of such a phase, recently predicted by Mambrini et al. [Phys. Rev. B 74, 144422 (2006)], we estimate its extent by Dlog-Pad'e analysis of the critical lines that result from closure of the triplet gap.