Non-linear spin wave theory results for the frustrated S=1/2 Heisenberg antiferromagnet on a body-centered cubic lattice

At zero temperature the sublattice magnetization of the quantum spin- 1/2 Heisenberg antiferromagnet on a body-centered cubic lattice with competing first and second neighbor exchange (J1 and J2) is investigated using the non-linear spin wave theory. The zero temperature phases of the model consist of a two sublattice Neel phase for small J2 (AF1) and a collinear phase at large J2 (AF2). We show that quartic corrections due to spin wave interactions enhance the sublattice magnetization in both the AF1 and the AF2 phase. The magnetization corrections are prominent near the classical transition point of the model and in the J2>J1 regime. The ground state energy with quartic interactions is also calculated. It is found that up to quartic corrections the first order phase transition (previously observed in this model) between the AF1 and the AF2 phase survives.