The spin-SAF transition in induced by spin-pseudospin couplingC. Gros1 and G. Y. Chitov1, 2
1 Fakultät 7, Theoretische Physik, University of the Saarland 66041 Saarbrücken, Germany
2 Department of Physics and Astronomy, Laurentian University 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada
received 2 September 2004; accepted in final form 23 November 2004
published online 24 December 2004
We present microscopic estimates for the spin-spin and spin-pseudospin interactions of the quarter-filled ladder compound , obtained by exactly diagonalizing appropriate clusters of the underlying generalized Hubbard Hamiltonian. We present evidence for a substantial interladder spin-pseudospin interaction term which would allow simultaneously for the superantiferroelectric (SAF) charge (pseudospin) ordering and spin dimerization. We discuss the values of the coupling constants appropriate for and deduce the absence of a soft antiferroelectric mode.
75.10.Jm - Quantized spin models.
75.40.Mg - Numerical simulation studies.
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