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Applied Physics Letters 81 (10): 1851-1853 (2002)

Synthesis and properties of c-axis oriented epitaxial MgB2 thin films

S D Bu , D M Kim , J H Choi , J Giencke , E E Hellstrom , D C Larbalestier , S Patnaik , L Cooley , C B Eom , J Lettieri , D G Schlom , W Tian , X Q Pan
We report the growth and properties of epitaxial MgB2 thin films on (0001) Al2O3 substrates. The MgB2 thin films were prepared by depositing boron films via radio-frequency (rf) magnetron sputtering, followed by a postdeposition anneal at 850C in magnesium vapor. X-ray diffraction and cross-sectional transmission electron microscopy reveal that the epitaxial MgB2 films are oriented with their c-axis normal to the (0001) Al2O3 substrate with a 30 rotation in the (0001) plane with respect to the substrate. The critical temperature was found to be 35 K and the anisotropy ratio, Hc2 /Hc2, was about 3 at 25 K. The critical current densities at 4.2 and 20 K (at 1 T perpendicular magnetic field) are 5106 and 1106A/cm2, respectively. The controlled growth of epitaxial MgB2 thin films opens a new avenue in both understanding superconductivity in MgB2 and technological applications. 2002 American Institute of Physics.
ISSN: 00036951     
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