Multiple Andreev reflection in single-atom niobium junctions

Article

关键词: QUANTUM TRANSPORT;    TUNNEL-JUNCTIONS;    POINT CONTACTS;    GAP STRUCTURE;    CONDUCTANCE;    VOLTAGE;    SIGNATURE;    CHANNEL;    BARRIER;    WIRES;   

DOI  :  10.1103/PhysRevB.61.8561

来源: SCIE

【 摘 要 】

Single-atom junctions between superconducting niobium leads are produced using the mechanically controllable break junction technique. The current-voltage characteristics of these junctions are analyzed using an exact formulation for a superconducting quantum point contact. For tunneling between two single atoms with a sufficiently large vacuum barrier, it is found that a single channel dominates the current, and that the current-voltage characteristic is described by the theory, without adjustable parameters. For a contact of a single Nb atom it is shown that five conductance channels contribute to the conductance, in agreement with the number expected based on the number of valence orbitals for this d metal. For each of the channels the transmission probability is obtained from the fits, and the limits of accuracy of these numbers are discussed.

【 授权许可】

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