Self-energy analysis of multiple-bosonic mode coupling in Sr sub(2RuO) sub(4)

We report angle-resolved photoemission spectroscopy studies on Sr sub(2RuO) sub(4). We observe multiple-bosonic mode coupling in the [alpha] and [beta] band dispersions. To extract the self-energy from the data for which the usual fitting methods do not work well, we propose a scheme that exploits the relation between the spectral intensity and self-energy, termed as relative self-energy. The relative self-energy obtained in that way contains important features of the self-energy. We observe not only the features that can be obtained from the band dispersions but also additional features that were not seen.