Electrical conduction mechanisms of metal / high-Tc superconductor (YBCO) interfaces

L. F. LANOSA; H. HUHTINEN; P. PATURI; C. ACHA

JOURNAL OF PHYSICS CONDENSED MATTER

IOP PUBLISHING LTD

Lugar: Londres; Año: 2020

0953-8984

Current-voltage characteristics of Au~/~YBa$_2$Cu$_3$O$_{7-\delta}$interfaces (Au/YBCO), built on optimally-doped YBCO thin films,grown by pulsed laser deposition, were measured as a function oftemperature in the 50 K to 270 K range, for two different resistancestates. A non-trivial equivalent circuit model is proposed, whichreveals the existence of a highly inhomogeneous scenario composed bytwo complex layers: one presenting both a non-linear Poole-Frenkelconduction as well as Variable Range Hopping localization effects(probably associated with YBa$_2$Cu$_3$O$_{6}$) mixed with a minormetallic phase, while the other is also composed by a mixture ofYBCO with different oxygen contents, where a metallic ohmic phasestill percolates. A microscopic description of the effects producedby the resistance switching is given, showing the evolution ofcarrier traps, localization effects and dielectric behavior for eachstate. The dielectric behavior is interpreted in terms of aMaxwell-Wagner scenario.