A New Landscape of Multiple Dispersion Kinks in a High- T-c Cuprate Superconductor

作者：Anzai H^*; Arita M; Namatame H; Taniguchi M; Ishikado M; Fujita K; Ishida S; Uchida S; Ino A^*

来源：Scientific Reports, 2017, 7(1): 4830.

DOI：10.1038/s41598-017-04983-0

Conventional superconductivity is caused by electron-phonon coupling. The discovery of high-temperature superconductors raised the question of whether such strong electron-phonon coupling is realized in cuprates. Strong coupling with some collective excitation mode has been indicated by a dispersion "kink". However, there is intensive debate regarding whether the relevant coupling mode is a magnetic resonance mode or an oxygen buckling phonon mode. This ambiguity is a consequence of the energy of the main prominent kink. Here, we show a new landscape of dispersion kinks. We report that heavily overdoping a Bi2Sr2CaCu2O8+delta superconductor results in a decline of the conventional main kink and a rise of another sharp kink, along with substantial energy shifts of both. Notably, the latter kink can be ascribed only to an oxygen-breathing phonon. Hence, the multiple phonon branches provide a consistent account of our data set on the multiple kinks. Our results suggest that strong electron-phonon coupling and its dramatic change should be incorporated into or reconciled with scenarios for the evolution of high-Tc superconductivity.

• 出版日期2017-7-6