Momentum-dependent light scattering in a 2D Heisenberg antiferromagnet

Motivated by the achievements of the X -ray scattering technique, we analyzed the profile of the light scattering intensity R ( q, ω ) at a finite q in a 2D Heisenberg antiferromagnet. Previous Raman scattering studies at q = 0 identified the two-magnon peak in B 1 g scattering geometry. We found that the B 1 g peak disperses downwards at a finite q , and its intensity increases, reaching its maximum at q = q 0 = (0 , π ) and symmetry related points. In addition, the intensity in the A 1 g geometry becomes non-zero 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 intensity at q 0 . We found that the profile of R ( q 0 , ω ) is equivalent in A 1 g and B 1 g geometries.