ar X iv : m tr l - th / 9 41 20 02 v 1 2 D ec 1 99 4 Commensurate and modulated magnetic phases in orthorhombic A
نویسندگان
چکیده
Competing magnetically ordered structures in polymerized orthorhombic AC 60 are studied. A mean-field theory for the equilibrium phases is developed using an Ising model and a classical Heisenberg model to describe the competition between inter-and intra-chain magnetic order in the solid. In the Ising model, the limiting commensurate one-dimensional and three-dimensional phases are separated by a commensurate three-sublattice state and by two sectors containing higher-order commensurate phases. For the Heisenberg model the quasi-1D phase is never the equilibrium state; instead the 3D commensurate phases exhibits a transition to a continuum of coplanar spiral magnetic phases.
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