Bulg. J. Phys. vol.43 no.4 (2016), pp. 304-310

Field Theory of Anisotropic Layered Antiferromagnets

Dimo I. Uzunov
G. Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee Blvd., Sofia, BG-1784 Bulgaria
Abstract. We develop the field theory of antiferromagnets to layered structures on bct crystal lattices with nearest-neibour and next-nearest-neighbour ferro- and/or antiferromagnetic interactions. For this aim the field theoretical counterpart of a lattice Heisenberg model is derived by standard theoretical methods: Hubbard-Stratonovich transformation and a generalized mean-field approach. We shown that the inter-layer interactions are a pure thermal fluctuation effect whereas the ground state is characterized by a perfect in-layer antiferromagnetic order and a lack of inter-layer coupling. This is a demonstration of 2D-3D dimensional crossover which is supposed to occur in real antiferromagnets, for example, in the spin-dimer antiferromagnet BaCuSi2O6.

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