Epitaxial growth and critical currents in (013)/(103)- and (110)-oriented YBa{sub 2}Cu{sub 3}O{sub {ital x}} films
- Department of Electrical and Electronic Engineering, University of Nottingham, Nottingham NG7 2RD (United Kingdom)
- Daido Institute of Technology, Nagoya (Japan)
Thin films of YBa{sub 2}Cu{sub 3}O{sub {ital x}} were grown epitaxially on (110)-oriented SrTiO{sub 3} crystals using {ital in} {ital situ}, off-axis, rf magnetron sputter deposition. The films were investigated by x-ray diffraction, reflection high-energy electron diffraction, scanning electron microscopy, resistance-temperature, and critical current measurements. Depending on growth conditions, the films formed platelets oriented with YBa{sub 2}Cu{sub 3}O{sub {ital x}} (110) or (013)/(103) parallel to the (110) substrates. Direct comparison of simultaneous growth on (110)- and (100)-oriented substrates showed that the critical temperature was significantly less for growth on the (100) surface for the same growth conditions. This is ascribed to the more open structure of the (110) and (013)/(103) planes which allow more complete oxidation of the film during growth and cool down. For growth on (110) substrates and substrate temperatures below about 650 {degree}C the (110) orientation dominated; above 650 {degree}C the films were mainly (013) or (103) oriented. The critical current density for the (013)/(103)-oriented films was 0.25 MA cm{sup {minus}2} at 77 K. This compares with about 5 MA cm{sup {minus}2} for {ital J}{sub {ital c}} parallel to the {ital ab} plane and 10 kA cm{sup {minus}1} for {ital J}{sub {ital c}} parallel to the {ital c} axis. The temperature dependence of the (013)/(103) films was {ital J}{sub {ital c}}{proportional_to}(1{minus}{ital T}/{ital T}{sub {ital c}}){sup 3/2}, 0.9{ital T}{sub {ital c}}{lt}{ital T}{lt}{ital T}{sub {ital c}}. This suggests that the measured critical currents correspond to the depairing current, although intergranular twinning gives a similar temperature dependence. The overall results are discussed in relation to the nucleation and growth kinetics of the different epitaxial modes and also the effects of energetic particles on sputter deposition.
- OSTI ID:
- 115837
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 9 Vol. 52; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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