arXiv subjects

G. Falci

Publications and source records attributed to G. Falci.

56 records · Page 4Linked to original sources

arXiv1995

Andreev tunneling into a one-dimensional Josephson junction array

In this letter we consider Andreev tunneling between a normal metal and a one dimensional Josephson junction array with finite-range Coulomb energy. The $I-V$ characteristics strongly deviate from the classical linear Andreev current. We show that the non linear conductance possesses interesting scaling behavior when the chain undergoes a T=0 superconductor-insulator transition of Kosterlitz-Thouless-Berezinskii type. When the chain has quasi-long range order, the low lying excitation are gapless and the $I-V$ curves are power-law (the linear relation is recovered when charging energy can be disregarded). When the chain is in the insulating phase the Andreev current is blocked at a threshold which is proportional to the inverse correlation length in the chain (much lower than the Coulomb gap) and which vanishes at the transition point.

cond-mat↗

arXiv1994

Tunneling in the Electron Box in the Nonperturbative Regime

We study charging effects and tunneling in the single electron box. Tunneling mixes different charge states and in the nonperturbative regime the charge in the island may be strongly screened. When charge states are nearly degenerate the screening of the charge is strong even in the weak tunneling regime. Virtual tunneling processes reduce both the level splitting and the tunneling strength. The charge on the island and the decay rates are calculated. In the strong tunneling regime also nondegenerate states are affected by tunneling. Strong-coupling scaling renormalizes the effective capacitance, a result which we confirm by Monte Carlo simulations. The tunneling strength scales to smaller values into the regime where the weak-coupling scaling applies. We propose a two stage scaling procedure providing the unified picture for the problem. The scaling analysis is also extended to superconducting tunnel junctions with finite subgap conductance. (9 figures upon request)

cond-mat↗