High transition temperature superconductor/insulator bilayers for the development of ultra-fast electronics

Abstract

Microstructures and resistivity of cuprate/manganite bilayer deposited on SrTiO 3 substrate

Electrical transport across nanometric SrTiO3and BaTiO3barriers in conducting/insulator/conducting junctions

“…In addition, independently from the barrier thickness, similar J(V) dependences are observed for TJ with different sizes. This indicates that the same mechanism governs the electrical transport (the quality of the barrier is homogenous in the involved area), which is in agreement with our previous study where surfaces clean of defects for GBCO/ STO bilayers on areas as large as 100x100 µm 2 were reported [29].…”

Improving the Josephson energy in high-Tc superconducting junctions for ultra-fast electronics

“…Considering thickness fluctuations and effects produced by different interfaces stacking, it is expected that both effects contribute. As we have shown previously for GBCO/STO bilayers, the electrical conductivity at the border of 3D defects is significantly higher than the one in the terraces [29,30]. If the borders of the 3D defects are pinholes (short circuits), I c is originated by two contributions: Josephson I J (terraces) and pinholes I p (borders of 3D defects).…”

“…In addition to the thickness fluctuations, the properties of the junctions may be affected by the stacking order at the interfaces, oxygen vacancies and by crystalline defects [27,28]. The electronic homogeneity of the STO barrier as a function of the thickness was previously analyzed in GBCO/STO bilayers by conducting atomic force microscopy at room temperature [29]. Conductivity maps indicate higher values at the borders of 3D defects than in the terraces and a barrier thickness distribution width of 0.8 nm.…”

Josephson coupling in high-Tc superconducting junctions using ultra-thin BaTiO3 barriers

“…The GBCO / BTO bilayers show a surface topology with uniform terraces and some 3D defects mainly originated in defects coming from the bottom electrode [31,32]. The borders of 3D defect usually display higher electrical conductivity than terraces increasing the inhomogeneity in the properties of barrier [30,31]. The electrical conductivity across the barrier decreases as the thickness increases.…”

“…GBCO/BTO/GBCO trilayers were grown on (100) SrTiO 3 by sputtering as described in detail elsewhere [15,30,31]. The tunnel junctions were designed using 16 nm thick GBCO electrodes and a BTO barrier with a thickness (d BTO ) of 1 nm, 2 nm, 3 nm, and 4 nm.…”