Electron-phonon interaction in Sr₂ RuO₄ investigated by Raman scattering

Electron-phonon interaction of the apical oxygen vibration at 550 cm^-1 for Sr₂ RuO₄ has been investigated by the interference-model analysis between the electronic continuum and phonon excitation (Fano effect). The peak intensity of the apical oxygen vibration is suppressed for the (a,a) spectrum, compared with (c,c). This decrease is understood by the anisotropy of polarizability and the existence of electron-phonon interaction. Furthermore, the interaction also depends on the propagating direction of the phonon. That is, the electron-phonon interaction of the phonon propagating along the conduction plane is larger than that along out of plane. These results are related to the two-dimensional electronic character of Sr₂ RuO₄.