The phase transition of a disordered antiferromagnet with competing interactions
- 20 April 1988
- journal article
- Published by IOP Publishing in Journal of Physics C: Solid State Physics
- Vol. 21 (11) , 2215-2223
- https://doi.org/10.1088/0022-3719/21/11/012
Abstract
The disordered system Rb2MnxCr1-xCl4 has competing ferromagnetic and antiferromagnetic exchange interactions. The phase transition in a single crystal with x=0.75 has been studied by neutron scattering techniques at the Institut Laue-Langevin. The dominant interactions in this system are between nearest-neighbour ions in the two-dimensional magnetic sheets and the behaviour above the ordering temperature is consistent with that of a two-dimensional Heisenberg model. At 34 K there is a phase transition to an antiferromagnetic structure with three-dimensional ordering below which the spins align in the magnetic planes. The phase transition proceeds therefore because of a cross-over produced by the anisotropy and the small interactions between the magnetic sheets. The order parameter increases only slowly with decreasing temperature with beta =0.52+or-0.10. The reasons for this behaviour are discussed.Keywords
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