Anisotropic light-matter interactions in the single-crystal topological insulator bismuth selenide

Anisotropy of light-matter interactions in materials gives remarkable information about phonons and their interactions with electrons. We report angle-resolved polarization Raman spectroscopy of single crystal of ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ to obtain elements of Raman tensor for understanding strength of polarization along different crystallographic orientations. Intensity variation in polar plots corresponding to ${E}_{g}^{1} \ensuremath{\sim}37\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}, {A}_{1g}^{1} \ensuremath{\sim}71\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}, {E}_{g}^{2} \ensuremath{\sim}130\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$, and ${A}_{1g}^{2} \ensuremath{\sim}173\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$ suggests higher differential polarizability along the $bc$ plane. The polar plots and elements of Raman tensor provide evidence of fundamental electron-phonon (e-ph) and anisotropic light-matter interactions in ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$.