Ground state properties of the ferrimagnetic one and two-dimensional Heisenberg model: Influence of dimerization and competitive interactions

We use the Schwinger boson mean field theory to study the effect of frustration and dimerization in the quantum ferrimagnetic model in one and two-dimensions. We calculate the spin reduction, the gap of the antiferromagnetic branch, and the spin fluctuation at T = 0 K. At finite temperature, the long-range order is destroyed because of the disappearance of the Bose condensation. The free energy, the magnetic susceptibility and the spin correlations at T = 0 K, are calculated. The effects of frustration and dimerization are discussed. Copyright EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2013