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High resolution transmission electron microscopy of Ba1−xKxBiO3 superconductor-insulator-superconductor grain boundary tunnel junctions

Published online by Cambridge University Press:  31 January 2011

Siu-Wai Chan
Affiliation:
School of Engineering and Applied Science, Columbia University, New York, New York 10027
A. Kussmaul
Affiliation:
Lasertron Inc., Bedford, Massachusetts 01730
E. S. Hellman
Affiliation:
Lucent Technologies, Bell Laboratories, Murray Hill, New Jersey 07974
E. H. Hartford Jr.
Affiliation:
Lucent Technologies, Bell Laboratories, Murray Hill, New Jersey 07974
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High angle boundaries in Ba1−xKxBiO3 are superconductor-insulator-superconductor (SIS) Josephson tunnel junctions of a quality unequaled among the high temperature superconducting oxides. Electron microscopy of 24° [001] tilt boundaries reveals nominally symmetric and straight boundaries of aperiodic structure with reappearing structural units. Low {hk0} atomistic facets are predominant. A segregation layer of only 1 nm thick is identified straddling the boundary. This layer which forms naturally is insulating, pin-hole free, and surprisingly robust with a breakdown voltage which exceeds 1 × 106 V/cm, yet thin enough to allow quasiparticle tunneling, yielding reliable gap energies for theoretical comparison.

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Articles
Copyright
Copyright © Materials Research Society 1998

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