Condensed Matter Physics Seminar
Thursday, May 4, 2000, 2 p.m.
Plant Sciences Building, Room 1130
Anomalous Proximity Effect in Underdoped YBa2Cu3O6+x
(Indiana University Perdue Universtity Indianapolis)
Abstract: A near-field scanning optical microscope (NSOM)
was used to photogenerate 150-nm wide superconducting wires in underdoped
thin films of the RBa2Cu3O6+x family,
with R a rare-earth. The observation of the Josephson effect
for separations as large as 90 nm between two wires indicates the existence
of an anomalously large proximity effect. The experimental results
show that the underdoped insulating RBa2Cu3O6+x
is readily perturbed into the superconducting state. The magnetic
field dependence of the critical current of the junctions was found to
be consistent with the Josephson relationship IJ(phi )~sin(phi).
This result constrains the applicability of SO(5) theory to explain the
phase diagram of high critical temperature superconductors.
Host: Dennis Drew
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