Heisenberg antiferromagnet on a compressible square lattice

The damping of spin waves due to spin-phonon interaction in a spin-S Heisenberg antiferromagnet on a square lattice is calculated. The theory applies to the regimes where the sound velocities vs are small compared with magnon velocities vm, which is the case in antiferromagnetic high-Tc superconductor basis materials like YaBa2Cu3O6, and kξ much-gt 1, where k and ξ are wave vector and correlation length, respectively. It is concluded that the broad spectral feature of the two-magnon line observed in layered perovskites can be explained qualitatively as a consequence of spin-phonon interaction