P. Esquinazi

University of Leipzig

Viernes 1/4/2011, 14 hs
Aula Federman, 1er piso, Pabellón I 

The possibility of high-temperature superconductivity at surfaces and interfaces attracted the attention of the low-temperature community since the earliest 60 s . Evidence for hightemperature superconductivity at the interfaces between insu lating oxides as well as between Bi crystalline regions has been published in th e last few years. The existence of intrinsic, nonpercolative high-temperature su perconductivity in highly oriented pyrolytic graphite (HOPG) has been speculated in the last 10 years. Recently published studies revealed that the internal structure of HOPG is compo sed by a stack of ~50 nm thick crystalline graphite regions with interfaces runn ing parallel to the graphene layers. Magnetoresistance measurements near an inte rface between two crystalline graphite regions of a graphite flake as well as at micro-constrictions showed a behavior compatible with the existence of non-perc olative superconductivity with critical temperatures above 50K. In my talk I wil l present a summary of all these studies and new transport measurements on speci ally prepared very thin lamellas of HOPG, which provide evidence for the existen ce of two-dimensional Josephson-coupled superconducting regions with critical te mperatures above 100K. The overall results support the view that HOPG is a system with interfaces containing nonpercolative superconducting domai ns immersed in a semiconducting graphene-based matrix.