Tunneling spectroscopy study of YBa sub 2 Cu sub 3 O sub 7 thin films using a cryogenic scanning tunneling microscope

Journal Article · Tue May 01 00:00:00 EDT 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.41.8904· OSTI ID:7155045

Wilkins, R; Amman, M ^[1]; Soltis, R E ^[2]; Ben-Jacob, E ^[3]; Jaklevic, R C ^[2]

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1. Department of Physics, The University of Michigan, Ann Arbor, Michigan 48109 (USA)
2. Scientific Laboratory, The Ford Motor Company, Dearborn, Michigan 48121 (USA)
3. Department of Physics, The University of Michigan, Ann Arbor, Michigan 48109 (USA) Scientific Laboratory, The Ford Motor Company, Dearborn, Michigan 48121 (USA)

We have measured reproducible tunneling spectra on YBa{sub 2}Cu{sub 3}O{sub 7} ({ital T}{sub {ital c}}{similar to}85 K) thin films (thickness {similar to}2 {mu}m) with a cryogenic scanning tunneling microscope. We find that the {ital I}-{ital V} curves are generally of three types. The most common type, featured in a large majority of the data, shows a region of high conductance at zero bias. The amplitude of this region is inversely proportional to the tunneling resistance between the tip and sample. It is possible that this can be explained in terms of Josephson effects within the films, although an alternative is given based on electronic self-energy corrections. Data showing capacitive charging steps are analyzed in terms of two ultrasmall tunnel junctions in series.. Theoretical fits to the data give specific values of the junction parameters that are consistent with the assumed geometry of the tip probing an individual grain of the film. The third type of {ital I}-{ital V} curves exhibits negative differential resistance. We conclude that this phenomenon is probably due to tunneling to localized states in the surface oxide. We also present and discuss data with energy-gap-like behavior; the best example gives {Delta} to be about 27 mV.

• OSTI ID: 7155045
• Journal Information: Physical Review, B: Condensed Matter; (USA), Vol. 41:13; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
TUNNEL EFFECT
COPPER OXIDES
YTTRIUM OXIDES
ELECTRIC CONDUCTIVITY
ENERGY GAP
JOSEPHSON EFFECT
SCANNING ELECTRON MICROSCOPY
THIN FILMS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
ELECTRICAL PROPERTIES
ELECTRON MICROSCOPY
FILMS
MICROSCOPY
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties