Biconical structures in two-dimensional anisotropic Heisenberg antiferromagnets

Abstract

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.

4 pages, 5 figures, accepted by Phys. Rev. B

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Cited by in corpus (10)

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• Spin-1 Heisenberg antiferromagnetic chain with exchange and single-ion anisotropies
• Uniaxially anisotropic antiferromagnets in a field on a square lattice
• Universal behavior of coupled order parameters below three dimensions
• Heisenberg antiferromagnets with uniaxial exchange and cubic anisotropies in a field
• Switching of anisotropy and phase diagram of a Heisenberg square lattice S=1/2 antiferromagnet Cu(pz)2(ClO4)2
• Phase diagram and multicritical behaviors of mixtures of 3D bosonic gases
• Ground state properties of antiferromagnetic anisotropic S=1 Heisenberg spin chains
• Quantum Heisenberg antiferromagnetic chains with exchange and single--ion anisotropies
• Layer Pseudospin Magnetism in Transition-Metal-Dichalcogenide Double-Moirés