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

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

JOURNAL OF PHYSICS CONDENSED MATTER

IOP PUBLISHING LTD

Año: 2020 vol. 32

0953-8984

Current?voltage characteristics of Au/YBa2Cu3O7− interfaces (Au/YBCO), built onoptimally-doped YBCO thin films, grown by pulsed laser deposition, were measured as afunction of temperature in the 50 K to 270 K range, for two different resistance states. Anon-trivial equivalent circuit model is proposed, which reveals the existence of a highlyinhomogeneous scenario composed by two complex layers: one presenting both a non-linearPoole?Frenkel conduction as well as variable range hopping localization effects (probablyassociated with YBa2Cu3O6) mixed with a minor metallic phase, while the other is alsocomposed by a mixture of YBCO with different oxygen contents, where a metallic ohmicphase still percolates. A microscopic description of the effects produced by the resistanceswitching is given, showing the evolution of carrier traps, localization effects and dielectricbehavior for each state. The dielectric behavior is interpreted in terms of a Maxwell?Wagnerscenario.