Atomic force microscopy study of the fractal shape of residual barium cuprate/copper oxide flux on the surface of Y[sub 2]Ba[sub 4]Cu[sub 7]O[sub 15] and YBa[sub 2]Cu[sub 4]O[sub 8] single crystals

Journal Article · Sun May 01 00:00:00 EDT 1994 · Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States)

DOI:https://doi.org/10.1116/1.587244· OSTI ID:6658531

Lang, H P ^[1]; Karpinski, J; Kaldis, E ^[2]; Ramseyer, J; Guentherodt, H ^[3]

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1. Institute of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland)
2. Swiss Federal Institute of Technology, Solid State Physics Laboratory, CH-8093 Zuerich (Switzerland)
3. Institute of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel (Switzerland)

Atomic force microscopy has been applied to study the surfaces of Y[sub 2]Ba[sub 4]Cu[sub 7]O[sub 15] (247) and YBa[sub 2]Cu[sub 4]O[sub 8] (124) high-temperature superconductor single crystals at ambient temperature and pressure. In contrast to very thin ([lt]10 [mu]m) crystal platelets, which exhibit by scanning tunneling microscopy clean terraces with steps of the height of one or multiple unit cells, thicker crystals show surfaces partially covered by a contamination layer with a highly curved boundary line originating from BaCuO[sub 2]/CuO flux used to grow 124 and 247 single crystals under high oxygen pressure. The evaluation of the length of such flux boundaries by the box counting method reveals that they are fractal with a fractal dimension of about 1.4. Close to crystal steps, higher fractal dimensions are observed provided the terrace width is sufficiently large. The fact that the residual flux is always found on the lower terrace level of a crystal step allows discussion of a possible mechanism of flux migration on the crystal surface.

• OSTI ID: 6658531
• Journal Information: Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States), Vol. 12:3; ISSN 0734-211X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
SURFACE PROPERTIES
COPPER OXIDES
YTTRIUM OXIDES
AMBIENT TEMPERATURE
FRACTALS
HIGH-TC SUPERCONDUCTORS
MONOCRYSTALS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
CRYSTALS
OXIDES
OXYGEN COMPOUNDS
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies