Eur. Phys. J. B 41, 67-74 (2004)
https://doi.org/10.1140/epjb/e2004-00295-5

Exact solution and magnetic properties of an anisotropic spin ladder

¹ Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ, Brasil
² Department of Physics, Hangzhou Teachers College, Hangzhou 310012, P.R. China
³ Instituto de Física da UFRGS, Av. Bento Gonçalves 9500, Porto Alegre, 91501-970, Brasil

Corresponding author: ^a ying@cbpf.br

Received: 20 March 2004
Revised: 21 May 2004
Published online: 30 September 2004

Abstract

We study an integrable two-leg spin-1/2 ladder with an XYZ-type rung interaction. The exact rung states and rung energies are obtained for the anisotropic rung coupling in the presence of a magnetic field. The magnetic properties are analyzed at both zero and finite temperatures via the thermodynamic Bethe ansatz and the high-temperature expansion. According to different couplings in the anisotropic rung interaction, there are two cases in which a gap opens, where the ground state involves one or two components in the absence of a magnetic field. We obtain the analytic expressions of all critical fields for the field-induced quantum phase transitions (QPT). The anisotropic rung interaction leads to such effects as separated magnetizations and susceptibilities in different directions, lowered inflection points, and remnant weak variation of the magnetization after the last QPT.