Phonon anomalies in ab-plane optical conductivity of high-T-c superconductors

It is shown that a correlation between the positions of the c-axis longitudinal optic (LO(c)) phonons and ''notch''-like structures in the ab-plane conductivity of high-T-c superconductors results from phonon-mediated interaction between electrons in different layers. It is found that the relative size of the notches depends on lambda(ph)(Omega(ph)/gamma(ph)), where lambda(ph), Omega(ph), and gamma(ph) are the effective coupling strength, the frequency, and the width of the optical phonon which is responsible for the notch. Even for lambda(ph)approximate to 0.01 the effect can be large if the phonon is very sharp.