Temperature dependence of the Raman scattering in the two-dimensional Heisenberg antiferromagnet

We have analyzed the ${\mathit{B}}_{1\mathit{g}}$ finite-temperature Raman response of the antiferromagnetic Heisenberg model. For temperatures in the range of the experimental data obtained for ${\mathrm{La}}_2$ ${\mathrm{CuO}}_4$, i.e., between T=0 and a little higher than the Néel transition temperature ${\mathit{T}}_{\mathit{N}}$, we obtain a qualitatively good agreement with experimental measurements: the two-magnon energy is almost independent of the temperature, and its intensity decreases by approximately 20% when T is increased from 0 to T≥${\mathit{T}}_{\mathit{N}}$. For temperatures T∼(2–4)${\mathit{T}}_{\mathit{N}}$ corresponding to the undoped compound ${\mathrm{La}}_2$ ${\mathrm{CuO}}_4$ to the paramagnetic phase, the two-magnon peak is still recognizable, showing the nonsensitivity of the short-wavelength spin waves to the presence or absence of long-range magnetic order.