Spin-1 Antiferromagnetic Heisenberg Chains in an External Staggered Field

Дата и время публикации : 2000-07-11T15:54:04Z

Авторы публикации и институты :
Elisa Ercolessi
Giuseppe Morandi
Pierbiagio Pieri
Marco Roncaglia

Ссылка на журнал-издание: Phys. Rev. B 62, 14860 (2000)
Коментарии к cтатье: 23 pages, 3 figures, LaTeX
Первичная категория: cond-mat.str-el

Все категории : cond-mat.str-el

Краткий обзор статьи: We present in this paper a nonlinear sigma-model analysis of a spin-1 antiferromagnetic Heisenberg chain in an external commensurate staggered magnetic field. After rediscussing briefly and extending previous results for the staggered magnetization curve, the core of the paper is a novel calculation, at the tree level, of the Green functions of the model. We obtain precise results for the elementary excitation spectrum and in particular for the spin gaps in the transverse and longitudinal channels. It is shown that, while the spectral weight in the transverse channel is exhausted by a single magnon pole, in the longitudinal one, besides a magnon pole a two-magnon continuum appears as well whose weight is a stedily increasing function of the applied field, while the weight of the magnon decreases correspondingly. The balance between the two is governed by a sum rule that is derived and discussed. A detailed comparison with the present experimental and numerical (DMRG) status of the art as well as with previous analytical approaches is also made.

Category: Physics