Uniaxially anisotropic antiferromagnets in a field on a square lattice |
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Authors: | M Holtschneider W Selke |
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Institution: | (1) Institut für Theoretische Physik, Technische Hochschule RWTH Aachen, 52056 Aachen, Germany |
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Abstract: | 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. |
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Keywords: | 68 35 Rh Phase transitions and critical phenomena 75 10 Hk Classical spin models 05 10 Ln Monte Carlo methods |
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