Abstract
We analyze the ultrahigh-resolution laser angle-resolved photoemission spectroscopy intensity from the slightly underdoped BiSrCaCuO in the superconductive (SC) state. The momentum distribution curves were fitted at each energy employing the SC Green’s function along several cuts perpendicular to the Fermi surface with the tilt angle with respect to the nodal cut. The clear observation of particle-hole mixing was utilized such that the complex self-energy as a function of is directly obtained from the fitting. The obtained angle-resolved self-energy is then used to deduce the Eliashberg function in the diagonal channel by inverting the -wave Eliashberg equation using the maximum entropy method. Besides a broad featureless spectrum up to the cutoff energy , the deduced exhibits two peaks around 0.05 and 0.015 eV. The former and the broad feature are already present in the normal state, while the latter emerges only below . Both peaks become enhanced as is lowered or the angle moves away from the nodal direction. The implication of these findings is discussed.
- Received 2 June 2011
DOI:https://doi.org/10.1103/PhysRevB.84.104521
©2011 American Physical Society