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Spin Gap in Chains with Hidden Symmetries

M. N. Kiselev·D. N. Aristov·K. Kikoin
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Abstract

We investigate the formation of spin gap in one-dimensional models characterized by the groups with hidden dynamical symmetries. A family of two-parametric models of isotropic and anisotropic Spin-Rotator Chains characterized by SU(2)x SU(2) and SO(2)x SO(2)x Z_2 x Z_2 symmetries is introduced to describe the transition from SU(2) to SO(4) antiferromagnetic Heisenberg chain. The excitation spectrum is studied with the use of the Jordan-Wigner transformation generalized for o_4 algebra and by means of bosonization approach. Hidden discrete symmetries associated with invariance under various particle-hole transformations are discussed. We show that the spin gap in SRC Hamiltonians is characterized by the scaling dimension 2/3 in contrast to dimension 1 in conventional Haldane problem.

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M. N. Kiselev, D. N. Aristov, K. Kikoin. 2004-08-01. Spin Gap in Chains with Hidden Symmetries. https://doi.org/10.1103/physrevb.71.092404

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