Non-linear spin wave theory results for the frustrated Heisenberg antiferromagnet on a body-centered cubic lattice

Abstract

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 neighborexchange (J1 and J2) is investigated using the non-linear spin wave theory. The zero temperaturephases of the model consist of a two sublattice Néel phase for smallJ2 (AF1) and a collinearphase at large J2 (AF2). Weshow that quartic corrections due to spin wave interactions enhance the sublattice magnetization in boththe AF1 and the AF2 phase. The magnetization corrections are prominent near the classical transition point of the model andin the J2>J1 regime. The ground state energy with quartic interactions is also calculated. It is found that up toquartic corrections the first order phase transition (previously observed in this model) between theAF1 andthe AF2 phase survives.