1. Reactive metal overlayer formation on high‐temperature superconductors at 20 K
- Author
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Y. Kimachi, T. R. Ohno, Yoshikazu Hidaka, J. H. Weaver, and G. H. Kroll
- Subjects
High-temperature superconductivity ,Materials science ,Inorganic chemistry ,Analytical chemistry ,Nucleation ,General Physics and Astronomy ,chemistry.chemical_element ,Copper ,Overlayer ,law.invention ,Metal ,chemistry ,Transition metal ,law ,visual_art ,visual_art.visual_art_medium ,Thin film ,Deposition (law) - Abstract
Photoemission results demonstrate that atom deposition of Ti, Cr, and Cu at 20 K on the high‐temperature superconductors (HTSs) dramatically reduces interfacial reaction relative to 300 K growth but does not completely eliminate it. Thin Ti‐O or Cr‐O layers are formed during atom deposition of ∼2 A of Ti or Cr on YBa2Cu3O7 or Bi2Sr2Ca1Cu2O8 because oxygen is withdrawn from the Bi‐O and/or Cu‐O layers. Interfacial reactions are diffusion limited at 20 K, and metal overlayers nucleate on the reacted layers. These metal layers are more uniform than those grown at 300 K because clustering is suppressed. There is no additional disruption for Cr/HTS interfaces when warmed to 300 K, but increased disruption is evident for Ti/HTS interfaces. The differences reflect the stabilities of Cr and Ti in contact with their own interfacial oxide. Cu atom deposition on Bi2Sr2Ca1Cu208(100) at 20 K also leads to much less disruption than observed for deposition at 300 K.
- Published
- 1991
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