  A longstanding mystery in understanding cuprate superconductors is the
inconsistency between the experimental data measured by scanning tunneling
spectroscopy (STS) and angle-resolved photoemission spectroscopy (ARPES). In
particular, the gap between prominent side peaks observed in STS is much bigger
than the superconducting gap observed by ARPES measurements. Here, we reconcile
the two experimental techniques by generalising a theory which was previously
applied to zero-dimensional mesoscopic Kondo systems to strongly correlated
two-dimensional (2D) exotic superconductors. We show that the side peaks
observed in tunneling conductance measurements in all these materials have a
universal origin: They are formed by coherence-mediated tunneling under bias
and do not directly reflect the underlying density of states (DOS) of the
sample. We obtain theoretical predictions of the tunneling conductance and the
density of states of the sample simultaneously and show that for cuprate and
pnictide superconductors, the extracted sample DOS is consistent with the
superconducting gap measured by ARPES.
