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Non-perturbative effective field theory for two-leg antiferromagnetic spin ladders

D. C. Cabra·A. Dobry·G. L. Rossini
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Abstract

We study the long wavelength limit of a spin 1/2 Heisenberg antiferromagnetic two-leg ladder, treating the interchain coupling in a non-perturbative way. We perform a mean field analysis and then include exactly the fluctuations. This allows for a discussion of the phase diagram of the system and provides an effective field theory for the low energy excitations. The coset fermionic Lagrangian obtained corresponds to a perturbed SU(4)_1/U(1) Conformal Field Theory (CFT). This effective theory is naturally embedded in a SU(2)_2 x Z_2 CFT, where perturbations are easily identified in terms of conformal operators in the two sectors. Crossed and zig-zag ladders are also discussed using the same approach.

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D. C. Cabra, A. Dobry, G. L. Rossini. 2001-04-11. Non-perturbative effective field theory for two-leg antiferromagnetic spin ladders. https://doi.org/10.1103/physrevb.63.144408

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