Observation of band renormalization effects in hole-doped high-[formula presented] superconductors

We report a systematic high-resolution angle-resolved photoemission spectroscopy on high-[Formula presented] superconductors [Formula presented] ([Formula presented]) to study the origin of many-body interactions responsible for superconductivity. For [Formula presented] and 3, a sudden change in the energy dispersion, so called “kink”, becomes pronounced on approaching ([Formula presented]) in the superconducting state, while a kink appears only around the nodal direction in the normal state. For [Formula presented], the kink shows no significant temperature dependence even across [Formula presented]. This could suggest that the coupling of electrons with [Formula presented] magnetic mode is dominant in the superconducting state for multilayered cuprates, while the interactions at the normal state and that of single-layered cuprates have a different origin.