Growth of a -axis-oriented HgBa 2 CaCu 2 O x thin films by rapid quenching
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RAPID COMMUNICATIONS The purpose of this Rapid Communications section is to provide accelerated publication of important new results in the fields regularly covered by Journal of Materials Research. Rapid Communications cannot exceed four printed pages in length, including space allowed for title, figures, tables, references, and an abstract limited to about 100 words.
Growth of a-axis-oriented HgBa2CaCu2Ox thin films by rapid quenching S.H. Yuna) and U.O. Karlsson Department of Physics, Materials Physics, Royal Institute of Technology, SE-100 44 Stockholm, Sweden
B.J. Jo¨nsson and K.V. Rao Department of Condensed Matter Physics, Royal Institute of Technology, SE-100 44 Stockholm, Sweden
L.D. Madsen Department of Physics, Linko¨ping University, SE-58183 Linko¨ping, Sweden (Received 1 October 1998; accepted 18 May 1999)
High-quality a-axis-oriented HgBa2CaCu2Ox superconducting thin films have been grown on (100) LaAlO3 substrates using a modified conventional method that contains a short annealing time of 5 min, rapid-quenching process, and an alternative encapsulated approach. We found that the preferred orientations of HgBa2CaCu2Ox thin films can be controlled by rapid quenching at specific temperatures: 800, 700, 600, and 500 °C. The films rapidly quenched in water from 700 °C during a cooling cycle showed predominantly a-axis orientation perpendicular to the film surface. Phase was confirmed by x-ray diffraction pole figures. The a-axis films exhibited a zero-resistance transition temperature >120 K, which is comparable to epitaxial c-axis-oriented films.
In addition to film quality, the control of preferred crystalline orientation in high-temperature superconducting (HTSC) thin films on various substrates is important for microelectronic devices and investigations of their anisotropic properties. A number of studies on the control of the preferred orientation of the HTSC thin films have been reported,1–3 with the exception of Hg-based cuprate superconducting thin films. These films have proven to be difficult to grow reproducibly in a single-phase form because of air sensitivity of the cuprate (Ba-Ca-Cu-O) and the volatility of mercury. Such thin films have only been grown with c-axis orientation perpendicular to the film surface. Recently, Gasser et al.4 reported the growth of a-axis-oriented (Hg1−xRex)Ba2CaCu2Oy thin films. However, there has been no demonstration of their films having either a high transition temperature (Tc) or crystalline quality comparable to typical epitaxial c-axisoriented thin films.
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Present address: Applied Physics, Johannes-Kepler University Linz, A-4040 Linz, Austria. e-mail: [email protected] J. Mater. Res., Vol. 14, No. 8, Aug 1999
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In this report, the growth and physical properties of high quality a-axis-oriented HgBa2CaCu2Ox (Hg-1212) thin films on (100) LaAlO3 substrates are described. To reduce chemical reaction and interdiffusion between film and substrat
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