Effective nonfrustrated model of the antiferromagnetic spin-1/2 ladder

Abstract

The spin S = 1/2 Heisenberg model on the frustrated saw-tooth spin-chain formed by triangular structural elements is investigated. Using the numerical calculations of the finite scheme of zero-temperature density matrix renormalization group the dependence of the magnetization on the external field is obtained. The dependence of magnetization has several plateaus that correspond to the gaps of the energy spectrum. The effective non-frustrated model with a close energy spectrum away from phase transition points is constructed. The relations between the parameters of the effective model and the fields that correspond to plateaus of magnetization are obtained.