Why do the self-energy effects appear in the elastic tunneling conductance?
We show that under fairly general conditions the self-energy effects in the elastic tunneling conductance of a normal metal-insulator-normal metal junction arise from the dependence of the real part of the electron self-energy S(e,w) on noninteracting electron energy e. We corroborate this by considering two special cases: the case when S arises from electron-phonon interaction in a metal, and the case when S is due to electron-electron interaction in a disordered metal. A possible modification of the form of S given by the marginal Fermi liquid theory for the normal state of oxide superconductors is suggested, if this theory is to account for the observed linear background tunneling conductance. Solid State Communications 82, 107-110, 1992.
