SMALL-SIZE TUNNELING CONTACTS WITH SUPERCONDUCTORS

Tunneling conductivity in SC-I-metal tip junction of nanometer scale i n the presence of an impurity state is examined theoretically by means of diagram technique for nonequilibrium processes. The theory takes i nto account two important factors: modification of the initial electro nic spectrum of superconductor and finite relaxation rates for a noneq uilibrium electronic density. The proposed model can be applied to var ious experimental situations, including STM/STS investigations of a cl ean SC surface. It is shown that in many cases dI/dV dependencies are essentially modified and gap structure is distorted. (C) 1998 Publishe d by Elsevier Science Ltd. All rights reserved.