Momentum-dependent light scattering in a two-dimensional Heisenberg antiferromagnet: Analysis of x-ray scattering data

Motivated by the achievements of the x-ray scattering technique, we analyzed the profile of the light scattering cross section R(q,omega) at a finite q in a 2D Heisenberg antiferromagnet. Previous Raman scattering studies at q=0 identified the two-magnon peak in B-1g scattering geometry. We found that the B-1g peak disperses downwards at a finite q, and its cross section increases, reaching its maximum at q=q(0)=(0,pi) and symmetry related points. In addition, the cross-section in the A(1g) geometry becomes nonzero at a finite q, and also displays a two-magnon peak which gains strength and disperses to larger frequencies with increasing q, and reaches its highest cross section at q(0). We found that the profile of R(q(0),omega) is equivalent in A(1g) and B-1g geometries.