Conductivity and Interferometry Experiments on YBCO/lead Ramp-Edge Josephson Junctions

Hilliard, Joseph Edward, Jr.

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Description

Title

Conductivity and Interferometry Experiments on YBCO/lead Ramp-Edge Josephson Junctions

Author(s)

Hilliard, Joseph Edward, Jr.

Issue Date

2001

Doctoral Committee Chair(s)

Van Harlingen, Dale J.

Department of Study

Physics

Discipline

Physics

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Physics, Condensed Matter

Language

eng

Abstract

In this thesis, we study the details of the order parameter symmetry in arbitrary directions of the high-temperature cuprate superconductor YBa 2Cu3O7-y (YBCO) using YBCO/Pb ramp-edge Josephson junctions with lithographically defined corner and straight-edge geometries. Measurements of the critical current versus applied field, I c(H), and the an dynamic conductance, dI/dV, are presented. For junctions with corner geometries, as well as for most of the straight-edge junctions, the known dx2-y2 order parameter symmetry of YBCO is confirmed. For some of the straight-edge junctions oriented near 45° with respect to the YBCO a and b axes, an anomalous temperature dependence of the Ic(H) pattern is found in the range from 5 down to 1.4 K. We consider the onset of a secondary order parameter and the onset of second-order Josephson coupling as possible interpretations of this anomalous temperature dependence and we find the second-order Josephson coupling interpretation more likely.

Graduation Semester

2001

Type of Resource

text

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http://hdl.handle.net/2142/80469

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