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Production of Weak Links in Superconducting Thin Films by Ion Implantation

IP.com Disclosure Number: IPCOM000082904D
Original Publication Date: 1975-Feb-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Harris, EP: AUTHOR [+2]

Abstract

Josephson effects are observed in structures in which two superconductors are weakly coupled together. A number of methods have been used in the past to produce the desired weak coupling. For example, a funneling barrier between two superconductors can act as a weak link.(1) Also, a small region in a superconducting film can have its transition temperature (T(c)) reduced by superimposing a normal metal film; this small region acts as a weak link between the superconducting films on either side./2/

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Production of Weak Links in Superconducting Thin Films by Ion Implantation

Josephson effects are observed in structures in which two superconductors are weakly coupled together. A number of methods have been used in the past to produce the desired weak coupling. For example, a funneling barrier between two superconductors can act as a weak link.(1) Also, a small region in a superconducting film can have its transition temperature (T(c)) reduced by superimposing a normal metal film; this small region acts as a weak link between the superconducting films on either side./2/

Described is the production of weak links in superconducting films by ion implantation of impurities in small regions, in order to depress T(c) in such localized regions. These regions then act as weak links. As an example, Mn atoms may be implanted into a Pb film to produce a weak link, as shown in Fig.
1. It is known that T(c) for Pb is reduced over 50% by doping with 0.2 atomic percent of Mn.(3) This large reduction in T(c) is due to the fact that Mn impurity atoms are magnetic.

A wide variety of atomic species are available for implantation, and other dopants and superconductors are also suitable. This method of making weak links has advantages over conventional techniques: (1) No ultrathin insulating layers are required; and (2) Technical problems involved in etching microbridge structures or small mesas or slots in normal or superconducting films (as in Ref.
3) are avoided.

Superconducting...