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Proceedings Paper

Magnetic properties of one-dimensional parallel arrays of Josephson junctions
Author(s): John H. Miller Jr.; Gemunu H. Gunaratne; Zhongji Zou; Matthew F. Davis; H. Regan Rampersad; Nong-Qiang Fan; John Charles Wolfe
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Paper Abstract

A superconducting quantum interference grating (SQUIG), consisting of many Josephson junctions in parallel, exhibits quantum interference analogous to the optical interference pattern produced by a diffraction grating, just as the dc SQUID is the magnetic analog of the double slit in optics. The field- dependent critical current of a SQUIG with sufficiently low inductance exhibits a series of sharp peaks, similar to the position-dependent intensity of a multiple-slit interference pattern. Such a device has the potential for improved sensitivity as a magnetic sensor because of its enhanced flux-to-voltage transfer coefficient. The behavior is quite different, however, when the inductance is large. In this limit, the field-dependent critical current becomes extremely hysteretic and exhibits self- organized phase coherence, in which a peak in the critical current (indicating coherence of the junction phases) is observed after each reversal of the field sweep. We have observed this phenomenon in large inductance arrays with up to ten YBa2Cu3O7 (YBCO) bi-crystal grain boundary junctions in parallel. We have modeled the behavior using a Frenkel-Kontorova model generalized to include global interactions due to mutual inductance. According to our model calculations, self-organized phase coherence occurs when the system relaxes from its critical state, causing the phases to simultaneously relax to minima in the periodic potential representing the Josephson coupling energy, and thus to become coherent modulo 2(pi) .

Paper Details

Date Published: 2 July 1994
PDF: 8 pages
Proc. SPIE 2160, Superconductive Devices and Circuits, (2 July 1994); doi: 10.1117/12.180987
Show Author Affiliations
John H. Miller Jr., Univ. of Houston (United States)
Gemunu H. Gunaratne, Univ. of Houston (United States)
Zhongji Zou, Univ. of Houston (United States)
Matthew F. Davis, Univ. of Houston (United States)
H. Regan Rampersad, Univ. of Houston (United States)
Nong-Qiang Fan, Univ. of Houston (United States)
John Charles Wolfe, Univ. of Houston (United States)

Published in SPIE Proceedings Vol. 2160:
Superconductive Devices and Circuits
Robert A. Buhrman; John T. Clarke; Ken Daly; Roger H. Koch; Jerome A. Luine; Randy W. Simon, Editor(s)

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