2010/06/30 by M. Mourigal, M. E. Zhitomirsky, A. L. Chernyshev · 3 citations
Physics and Astronomy · #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.82.144402
published as Phys. Rev. B, 82, 144402 (2010) · 12 pages, 11 figures, final version
arxiv created 2010/10/01 · arxiv updated 2010/10/04
Dynamical properties of the square-lattice Heisenberg antiferromagnet in applied magnetic field are studied for arbitrary value S of the spin. Above the threshold field for two-particle decays, the standard spin-wave theory yields singular corrections to the excitation spectrum with logarithmic divergences for certain momenta. We develop a self-consistent approximation applicable for S >= 1, which avoids such singularities and provides regularized magnon decay rates. Results for the dynamical structure factor obtained in this approach are presented for S = 1 and S = 5/2.