Characterization of the insulator barrier and the superconducting transition temperature in GdBa{sub 2}Cu{sub 3}O{sub 7−δ}/BaTiO{sub 3} bilayers for application in tunnel junctions

Journal Article · Tue Jul 28 00:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4927751· OSTI ID:22494671

Sirena, M.; Haberkorn, N. ^[1]; Yang, Ilkyu ^[2]; Kim, Jeehoon ^[2]

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1. Instituto Balseiro, Universidad Nacional de Cuyo and CNEA, 8400 Bariloche (Argentina)
2. Department of Physics, Pohang University of Science and Technology, Pohang (Korea, Republic of)

The optimization of the superconducting properties in a bottom electrode and the quality of an insulator barrier are the first steps in the development of superconductor/insulator/superconductor tunnel junctions. Here, we study the quality of a BaTiO{sub 3} tunnel barrier deposited on a 16 nm thick GdBa{sub 2}Cu{sub 3}O{sub 7−δ} thin film by using conductive atomic force microscopy. We find that the tunnel current is systematically reduced (for equal applied voltage) by increasing the BaTiO{sub 3} barrier thickness between 1.6 and 4 nm. The BaTiO{sub 3} layers present an energy barrier of ≈1.2 eV and an attenuation length of 0.35–0.5 nm (depending on the applied voltage). The GdBa{sub 2}Cu{sub 3}O{sub 7−δ} electrode is totally covered by a BaTiO{sub 3} thickness above 3 nm. The presence of ferroelectricity was verified by piezoresponse force microscopy for a 4 nm thick BaTiO{sub 3} top layer. The superconducting transition temperature of the bilayers is systematically suppressed by increasing the BaTiO{sub 3} thickness. This fact can be associated with stress at the interface and a reduction of the orthorhombicity of the GdBa{sub 2}Cu{sub 3}O{sub 7−δ}. The reduction in the orthorhombicity is expected by considering the interface mismatch and it can also be affected by reduced oxygen stoichiometry (poor oxygen diffusion across the BaTiO{sub 3} barrier)

• OSTI ID: 22494671
• Journal Information: Journal of Applied Physics, Vol. 118, Issue 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATOMIC FORCE MICROSCOPY
ATTENUATION
BARIUM COMPOUNDS
CUPRATES
DEPOSITION
ELECTRIC POTENTIAL
ELECTRICAL INSULATORS
ELECTRODES
EV RANGE
GADOLINIUM COMPOUNDS
LAYERS
OXYGEN
STOICHIOMETRY
STRESSES
SUPERCONDUCTORS
THICKNESS
THIN FILMS
TITANATES
TRANSITION TEMPERATURE
TUNNEL JUNCTIONS