| As a direct measure of the electronic interactions in a solid, knowledge of the electronic scattering rates is essential for understanding a material's behavior. Since angle resolved photoemission spectroscopy (ARPES) can probe an individual momentum state, it holds great promise for the most detailed and accurate measurements of the k-dependent electron scattering rates. Unfortunately, the scattering rates determined from ARPES are typically an order of magnitude greater than those obtained from other probes, (e.g. optical spectroscopy). Here we present a new type of spectrum, the ARPES tunneling spectrum (ATS), which resolves this discrepancy, as well as provides a qualitatively different understanding of the electronic interactions in the cuprates. We find that the electronic states at the Fermi surface are governed by not one but two energy scales, the gapping order parameter and the pair-breaking scattering rate. We find that much of the exotic phenomena found in the cuprates, such as Fermi arcs, pseudogaps and two gap models can trace their origin to the interplay between these two energy scales. |
