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Phase Diagram of the Spin-Orbital model on the Square Lattice

E. Zasinas·O. P. Sushkov·J. Oitmaa
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Abstract

We study the phase diagram of the spin-orbital model in both the weak and strong limits of the quartic spin-orbital exchange interaction. This allows us to study quantum phase transitions in the model and to approach from both sides the most interesting intermediate-coupling regime and in particular the SU(4)-symmetric point of the Hamiltonian. It was suggested earlier by Li et al [Phys.Rev.Lett. vol. 81, 3527 (1999)] that at this point the ground state of the system is a plaquette spin-orbital liquid. We argue that the state is more complex. There is plaquette order, but it is anisotropic: bonds in one direction are stronger than those in the perpendicular direction. This order is somewhat similar to that found recently in the frustrated J_1-J_2 Heisenberg spin model.

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E. Zasinas, O. P. Sushkov, J. Oitmaa. 2001-05-09. Phase Diagram of the Spin-Orbital model on the Square Lattice. https://doi.org/10.1103/physrevb.64.184431

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