Raman scattering through surfaces having biaxial symmetry

Magnetic Raman scattering in two-leg spin ladder materials and the relationship between the anisotropic exchange integrals are analyzed by P. J. Freitas and R. R. P. Singh [Phys. Rev. B 62, 14113 (2000)]. The angular dependence of the two-magnon scattering is shown to provide information for the magnetic anisotropy in the Sr₁₄Cu₂₄O₄₁ and La₆Ca₈Cu₂₄O₄₁ compounds. We point out that the experimental results of polarized Raman measurements at arbitrary angles with respect to the crystal axes have to be corrected for the light ellipticity induced inside the optically anisotropic crystals. We refer quantitatively to the case of Sr₁₄Cu₂₄O₄₁ and briefly discuss potential implications for spectroscopic studies in other materials with strong anisotropy.