Condensed Matter Physics Seminar

Thursday, May 4, 2000, 2 p.m.
Plant Sciences Building, Room 1130

Anomalous Proximity Effect in Underdoped YBa2Cu3O6+x Josephson Junctions

Ricardo Decca

(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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