Effects of competing interactions on low-energy characteristics of a spin-½ cubic cluster

Abstract

We consider a simple cubic magnetic cluster with spin-½ ions at its eight corners. The superexchange Hamiltonian employed in this paper involves nearest, next-nearest (nn), and next to next-nearest (nnn) neighbour interactions. These competing exchange interactions are found to generate a number of phases with ground states: (a) ferromagnetic; (b) nn-neighbour dimers; (c) regular antiferromagnetic; (d) nnn-neighbour dimers; and (e) nnn-neighbour forming triplets. We have also found fully polarized and partially polarized lowest spin excitations in the broken symmetry phases. The effects of the low-energy characteristics in various phases have been quantified by computing thermodynamic properties, such as magnetization and susceptibility.