Eur. Phys. J. B 59, 285-289 (2007)
https://doi.org/10.1140/epjb/e2007-00289-9

Gap-behavior in the vicinity of a saturation transverse field

Institute for Advanced Studies in Basic Sciences, Zanjan, 45195-1159, Iran

Corresponding author: ^a mahdavifar@iasbs.ac.ir

Received: 10 January 2007
Revised: 13 June 2007
Published online: 17 October 2007

Abstract

We have studied the behavior of the energy gap of the 1D AF spin- XXZ model in a transverse magnetic field (h) using the exact diagonalization technique. The ground state phase diagram consists of two spin-flop and paramagnetic phases. Using a modified finite-size scaling approach, we have computed the critical exponent of the energy gap in the vicinity of the critical transverse field h_c(Δ). Our numerical results confirm that the continuous phase transition from the spin-flop phase to the paramagnetic one is in the universality class of the Ising model in the transverse field (ITF). By applying conformal estimates of a small perturbation (h≪1), we have also justified our numerical results.