RESONANT COULOMB SCREENING OF CHARGING OF A LOCALIZED STATE

I consider the effect of Coulomb screening on the resonant tunneling through a localized nondegenerate state between two quasi-one-dimensional conductors. It occurs when the local value of the electron density varies significantly on the edges of the conductors. Then the screening becomes resonant and drastically modifies the properties of the localized state. In particular, it leads to the appearance of a hidden symmetry in the problem as a result of which the occupation number of the level nD is pinned to 1/2. This means that the level should exhibit resonant conductance (e2/h)sin2nD in a wide range of energies of the order of the Fermi energies of the conductors. In contrast to the Kondo effect, this effect of the resonant screening is much more stable against temperature and voltage fluctuations. This circumstance can be crucial for the experimental observation. The emergence of this effect in the behavior of impurities in metals is also possible and is briefly sketched. © 1995 The American Physical Society.