2007/10/31 by M. Holtschneider, W. Selke · 1 citation
Physics and Astronomy · #Advanced Condensed Matter Physics #Anisotropy #Antiferromagnetism #Classical XY model #Condensed matter physics #Degeneracy (biology) #Ground state #Heisenberg model #Ising model #Lattice (music) #Phase transition #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Spin (aerodynamics) #Square lattice #Theoretical and Computational Physics #cond-mat.stat-mech
paper · pdf · doi:10.1103/physrevb.76.220405
published as Phys. Rev. B 76, 220405(R) (2007) · 4 pages, 5 figures, accepted by Phys. Rev. B
openalex publication_date 2007/12/17 · arxiv created 2007/12/19 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Square lattice Heisenberg and XY antiferromagnets with uniaxial anisotropy are studied in a field along the easy axis. Based on ground-state considerations and Monte Carlo simulations, the role of biconical structures in the transition region between the antiferromagnetic and spin-flop phases is analyzed. In particular, on adding a single-ion anisotropy to the XXZ antiferromagnet, one observes, depending on the sign of that anisotropy, either an intervening biconical phase or a direct transition of first order separating the two phases. In the case of the anisotropic XY model, the degeneracy of the ground state, at a critical field, in antiferromagnetic, spin-flop, and bidirectional structures seems to result, as in the case of the XXZ model, in a narrow disordered phase between the antiferromagnetic and spin-flop phases, dominated by bidirectional fluctuations.