2008/03/23 by Rakesh Kumar, Brijesh Kumar
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.77.144413
published as Phys. Rev. B 77, 144413 (2008) · revtex4, 16 eps files; total 10 pages; accepted for publication in Phys. Rev. B
arxiv created 2008/03/23 · openalex publication_date 2008/04/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We construct and study the two frustrated quantum spin-1∕2 models on square lattice, which are like the antiferromagnetic J1\text\ensuremath-J2 model with some additional four-spin exchange interactions. These models admit an exactly solvable case in which the ground state consists of four degenerate columnar-dimer singlet (CDS) configurations. Away from the exact case, we employ bond-operator mean-field theory to investigate the evolution of the ground state by varying the interaction parameters. The mean-field calculation reveals a quantum phase diagram in which the CDS phase undergoes a continuous phase transition to either N'eel or collinear ordered antiferromagnetic phases.