Observation of band renormalization effects in hole-doped high-Tc superconductors -: art. no. 157003

We report a systematic high-resolution angle-resolved photoemission spectroscopy on high-T-c superconductors Bi2Sr2Can-1CunO2n+4 (n=1-3) to study the origin of many-body interactions responsible for superconductivity. For n=2 and 3, a sudden change in the energy dispersion, so called kink, becomes pronounced on approaching (pi,0) in the superconducting state, while a kink appears only around the nodal direction in the normal state. For n=1, the kink shows no significant temperature dependence even across T-c. This could suggest that the coupling of electrons with Q=(pi,pi) 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.