Biconical structures in two-dimensional anisotropic Heisenberg antiferromagnets
| Autor: | Holtschneider, M., Selke, W. |
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| Rok vydání: | 2007 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 76, 220405(R) (2007) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.76.220405 |
| Popis: | Square lattice Heisenberg and XY antiferromagnets with uniaxial anisotropy in a field along the easy axis are studied. 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, 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 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. Comment: 4 pages, 5 figures, accepted by Phys. Rev. B |
| Databáze: | arXiv |
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