Magnetoelastic instability in the XXZ rings with next-nearest neighbour coupling

Abstract

This paper numerically investigates the magnetoelastic instability in the S = 1/2 XXZ rings containing finite spins N with antiferromagnetic nearest-neighbour (NN) and next-nearest neighbour (NNN) coupling. It finds that, as the NN anisotropy Δ1 equals the NNN anisotropy Δ2, there exists a critical NNN coupling strength Jc2 (≈ 0.5), at which the systems always locate in dimerized phase for arbitrary large spring constant. As Δ1 ≠ Δ2, the values of Jc2 are dependent on N and the difference of (Δ1 – Δ2).