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Magnetization Plateaux in N-Leg Spin Ladders

D. C. Cabra·A. Honecker·P. Pujol
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Abstract

In this paper we continue and extend a systematic study of plateaux in magnetization curves of antiferromagnetic Heisenberg spin-1/2 ladders. We first review a bosonic field-theoretical formulation of a single XXZ-chain in the presence of a magnetic field, which is then used for an Abelian bosonization analysis of N weakly coupled chains. Predictions for the universality classes of the phase transitions at the plateaux boundaries are obtained in addition to a quantization condition for the value of the magnetization on a plateau. These results are complemented by and checked against strong-coupling expansions. Finally, we analyze the strong-coupling effective Hamiltonian for an odd number N of cylindrically coupled chains numerically. For N = 3 we explicitly observe a spin-gap with a massive spinon-type fundamental excitation and obtain indications that this gap probably survives the limit N to infinity.

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D. C. Cabra, A. Honecker, P. Pujol. 1998-06-30. Magnetization Plateaux in N-Leg Spin Ladders. https://doi.org/10.1103/physrevb.58.6241

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