https://doi.org/10.1140/epjb/e2008-00149-2
Uniaxially anisotropic antiferromagnets in a field on a square lattice
Institut für Theoretische Physik, Technische Hochschule RWTH Aachen, 52056 Aachen, Germany
Corresponding author: a selke@physik.rwth-aachen.de
Received:
21
January
2008
Revised:
3
March
2008
Published online:
11
April
2008
Classical uniaxially anisotropic Heisenberg and XY antiferromagnets in a field along the easy axis on a square lattice are analysed, applying ground state considerations and Monte Carlo techniques. The models are known to display antiferromagnetic and spin-flop phases. In the Heisenberg case, a single-ion anisotropy is added to the XXZ antiferromagnet, enhancing or competing with the uniaxial exchange anisotropy. Its effect on the stability of non-collinear structures of biconical type is studied. In the case of the anisotropic XY antiferromagnet, the transition region between the antiferromagnetic and spin-flop phases is found to be dominated by degenerate bidirectional fluctuations. The phase diagram is observed to resemble closely that of the XXZ antiferromagnet without single-ion anisotropy.
PACS: 68.35.Rh – Phase transitions and critical phenomena / 75.10.Hk – Classical spin models / 05.10.Ln – Monte Carlo methods
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008
