Single Vortex Motion and Elementary Pinning Force in SNIS Josephson Junctions [Dissertation]

Thesis/Dissertation · Thu Jul 18 04:00:00 EDT 1991

OSTI ID:5402912

Li, Qiang ^[1]

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1. Ames Lab., and Iowa State Univ., Ames, IA (United States)

A new family of superconductor – normal metal – insulator – superconductor (SNIS) Josephson junctions has been developed to study the motion of a single Abrikosov vortex under the influence of a Lorentz force from an applied transport current. The location of the vortex within the junction is determined by the diffraction pattern. Methods have been developed to nucleate a single vortex by applying a transport current in one strip of the junction and systematically to push the vortex to nearly any desired location within the junction by applying currents in either of the cross-strip legs of the junction. The vortex in thin film Pb was found to move stepwise from one pinning center to another. The average distance separating pinning centers in thin film Pb is about 1.0 μm. The elementary pinning force f_p for a vortex in a pure Pb film was measured to be on the order of 10^–13 N at reduced temperature t = T/T_c = 0.9, which is about one order of magnitude smaller than that for a Pb-Bi film at this reduced temperature. The temperature dependence of f_p was found to be f_p ~ (1–T/T_c) above 6.5 K and f_p ~ (1–T/T_c)^2/3 below 6.5 K. The feasibility of using the motion of a single vortex to store information and perform logic has been investigated. Since the Josephson voltage is in the range of tens of millivolts, the read and write operations can be done with rather simple electronics. 53 refs., 36 figs.

• Research Organization: Ames Laboratory (AMES), Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5402912
• Report Number(s): IS-T--1565; ON: DE91016160
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104 -- Metals & Alloys-- Physical Properties
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
426001* -- Engineering-- Superconducting Devices & Circuits-- (1990-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CRITICAL CURRENT
CURRENT DENSITY
CURRENTS
DATA ANALYSIS
ELECTRIC CURRENTS
ELEMENTS
FABRICATION
HIGH-TC SUPERCONDUCTORS
JOSEPHSON JUNCTIONS
JUNCTIONS
LEAD
MAGNETIC FLUX
METALS
SAMPLE PREPARATION
SUPERCONDUCTING JUNCTIONS
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
VORTICES