Eur. Phys. J. B 44, 169-174 (2005)
https://doi.org/10.1140/epjb/e2005-00111-x

Quantum fluctuations in low-dimensional easy-plane spin models

¹ Departamento de Física, ICEx, Universidade Federal de Minas Gerais CP 702, Belo Horizonte, CEP 30123-970, MG, Brazil
² Centro Federal de Educação Tecnológica de Minas Gerais, Belo Horizonte, MG, Brazil

Corresponding author: ^a meg@fisica.ufmg.br

Received: 23 December 2004
Published online: 20 April 2005

Abstract

A self-consistent harmonic approximation is used to treat the low temperature limit of the one and two dimensional S=1 easy plane magnets. For the one dimensional (1D) model, we calculate the gap caused by the presence of an external magnetic field applied in the easy-plane. The quantum phase transition of the one-dimensional model at T=0 is also studied. For the two-dimensional case, the Kosterlitz-Thouless (KT) transition temperature as a function of a single-ion anisotropy term is calculated. The line ends at a quantum critical point, where the KT temperature goes to zero.