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Opening of the Haldane Gap in Anisotropic Two- and Four-Leg Spin Ladders

Eugene H. Kim·J. Solyom
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Abstract

We study the opening of the Haldane gap in two-leg and four-leg anisotropic spin ladders using bosonization and renormalization group methods, and we determine the phase diagram as a function of the interchain coupling and the relative anisotropy. It is found that the opening of the Haldane gap is qualitatively different for the two cases considered. For the two-leg ladder the Haldane gap opens for arbitrarily small interchain coupling, independent of the relative anisotropy, and the Haldane phase exists in a large region of parameter space. For the four-leg ladder the opening of the Haldane gap is strongly dependent on both the interchain coupling as well as the relative anisotropy, and the Haldane phase exists only in a narrow region about the isotropic antiferromagnet.

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Eugene H. Kim, J. Solyom. 1999-03-16. Opening of the Haldane Gap in Anisotropic Two- and Four-Leg Spin Ladders. https://doi.org/10.1103/physrevb.60.15230

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